The biggest spectacle of any type of international exposition is often the architecture.

Given the ephemeral nature of world's fairs — the jaw-dropping, crowd-drawing structures erected for expos are also largely temporary. However, a small handful of buildings — sometimes, a single building — are built and designed to live on beyond the fair. With contemporary expos, it's usually the fair's "theme" building or the host country's national pavilion that sticks around while lesser buildings are dismantled and reused for other purposes.

And then there are the world's fair structures that, either intentionally or by happy accident, have not just stuck around but thrived in their post-expo afterlives as local and international landmarks, popular cultural institutions or off-kilter icons that leave people wondering "Where in the world did that come from?" The answer to that question, more often than not, is the world's fair.

We've rounded up 15 spectacular, sensational and, most important, still-standing architectural remainders from world's fairs past. All are pictured in their current state. Is there an extant expo structure — or singular sculpture — that we left out? Tell us about in the comments section.

1. The Eiffel Tower — 1889 Exposition Universalle, Paris

Jiuguang Wang [CC by 2.0]/flickr

Need we really explain the global magnitude of this landmark, this cliché, this towering feat of late 19th century engineering that screams je suis France!?

No, probably not. But unless they take the time to read the fine print, many visitors to La Tour Eiffel are unaware of the 1,063-foot-tall iron latticework tower's origins as a much hated-on work of temporary architectural razzle-dazzle meant to serve as the entrance arch — and what an arch it was — to the 1889 World's Fair. Many Parisians, the city's artists and coffee shop intelligentsia in particular, were fervently opposed to the thought of such a monstrosity — an entry in a design contest, nonetheless! — straddling their beloved Champ de Mars. There weren't quite riots in the street, but close.

Despite the backlash, engineer Gustave Eiffel marched forward with his plans and, several days after the 1889 Exposition Universalle kicked off, the Eiffel Tower – then home to a post office, a printing press and a pâtisserie — opened to the public. It was a hit. The tower's detractors — we imagine a group of grizzled old men in berets shaking their fists at the sky — likely found solace in the fact that the ephemeral monument was supposed to be dismantled in 1909 — 20 years after its grand debut when ownership was transferred over to the city. Paris officials, obviously, had one hell of a change of heart and decided that the once purely decorative tourist trap could also act as a massive radio antenna, a role that this "truly tragic streetlamp" has served since the early 20th century.

2. Palace of Fine Arts — Louisiana Purchase Exposition, St. Louis

Bettina Woolbright [CC by 2.0]/flickr

Sure it's not the Eiffel Tower. But St. Louis's Palace of Fine Arts, erected for 1904's Louisiana Purchase Exposition, is a magnificent work of civic architecture that's been continuously enjoyed by the public well beyond its world's fair run.

The crown jewel of Forest Park, a sprawling urban park littered with crown jewels, the Cass Gilbert-designed Palace of Fine Arts was the only permanent structure built for the St. Louis Fair, an event best known for popularizing noted health foods such as ice cream cones, cotton candy and Dr. Pepper. Just a couple short years after the conclusion of the fair, the Palace — "the one material monument of the Exposition" — reopened as the new home of the St. Louis Art Museum, an institution recognized as one of the premiere art museums in the U.S. It was around the same time that a bronze version of the Apotheosis of St. Louis, an equestrian statue that served as the official symbol of the city until the Gateway Arch came along, was installed in front of the newly minted museum. And while the Palace may be the only proper building from the St. Louis World's Fair standing in Forest Park, smaller relics still exist including the Saint Louis Zoo's Flight Cage aviary. A massive pipe organ and bronze eagle statue that both debuted at the fair went on to find a loving second home at Wanamaker’s department story in Philadelphia (now a Macy's, go figure). Both have become Philly icons.

3. Palace of Fine Arts — 1915 Panama-Pacific Exposition, San Francisco

miss_millions [CC by 2.0]/flickr

Up there with the Chinatown arch and the painted ladies of Alamo Square, the mysterious faux Roman ruins otherwise known as the Palace of the Fine Arts have served as the backdrop of a million and one Instagrams snapped in San Francisco.

Best known for its grand, Greco-Romanesque domed rotunda and colonnades set against a placid, swan-filled lagoon, the Palace was designed by Bernard Maybeck as a temporary structure — a pop-up museum, essentially, that would be referred to in inelegant, contemporary world's fair-speak as a "pavilion" — for the 1915 Panama-Pacific International Exposition, a public exercise in civil rebounding for San Francisco, a city decimated by earthquake and fire less than 10 years prior. While meant to come down immediately after the close of the fair, Phoebe Apperson Hearst, mother of William Randolph, rallied for the Palace to be preserved, not demolished. A commendable action, no doubt, but the structure itself wasn’t really meant to live on given that it was basically constructed from papier-mâché. By the 1950s, the Palace had reached an advanced state of decay. Instead of bulldozing over it completely, the city opted to rebuild the Palace using more durable materials (read: concrete) in 1964. In the years since, the Palace has experienced rough patches — and prolonged closures — but community-led restoration efforts have helped to keep the much-loved San Francisco landmark alive. This year, it's played a central role in the centennial celebrations of the 1915 World's Fair.

4. Magic Fountain of Montjuïc — 1929 Barcelona International Exposition

Glen Scarborough/[CC by 2.0]flickr

Mesmerizing, marvelous and a grade-A tourist magnet, visitors to Barcelona might be surprised to learn that the Magic Fountain of Montjuïc has been doing its thing — gorgeously illuminated evening performances — since 1929 when it was unveiled for the Barcelona International Exposition.

Situated on Avenida Maria Cristina directly below another stunning expo remainder, Palau Nacional, Barcelona's most iconic fountain — seriously, if you haven't seen water "dance" to "What a Feeling" than you haven't fully experienced Barcelona — has been altered very little over the years with the most significant change coming in the early 1980s when music was added to the nightly performances. In 1992, the Carles Buïgas-designed landmark was treated to a careful, pre-Summer Olympics restoration. A feat of the imagination that manages to put a certain watery Las Vegas spectacle to shame, Font màgica is one of several famous fountains to be created for world’s fairs. Other notable, still-remaining ones include Prague's Křižíkova fontána (the General Land Centennial Exhibition of 1891) and the International Fountain in Seattle (the 1962 World's Fair).

5. The Atomium — Expo 58, Brussels

amateur photography by michel [CC by 2.0]/flickr

Ah, the Atomium...a well-preserved world's fair relic so imposing, so bizarre-looking that it's unclear if you should move closer to — or run away from — it.

Originally built for Expo 58 in Brussels, the Atomium's official website sums up the significance of this "kind of UFO in the cultural history of humanity" best: "A seminal totem in the Brussels skyline; neither tower, nor pyramid, a little bit cubic, a little bit spherical, half-way between sculpture and architecture, a relic of the past with a determinedly futuristic look, museum and exhibition center; the Atomium is, at once, an object, a place, a space, a Utopia and the only symbol of its kind in the world, which eludes any kind of classification." Got it. Currently, the nine-sphered structure (technically, it's a 335-foot-tall representation of the single cell of an iron crystal) is home to a museum, observation area and panoramic restaurant serving traditional Belgian specialties such as Flemish leek whites and vol-au-vent chicken.

6. The Space Needle — 1962 World's Fair, Seattle

Maëlick [CC by 2.0]/flickr

Monorails! Cordless phones! Bubbleators! Elvis!

Developed as a dizzying, dazzling exercise in space age living, the wildly successful, not to mention prescient, Century 21 Exposition — better known as the Seattle's World Fair — was particularly action-packed as far as expos go. The event's lasting impact on host city Seattle is indelible: the fairgrounds, now a sprawling park and entertainment complex known as the Seattle Center, are still home to a number of retro-futuristic attractions (the International Fountain, KeyArena, built as the Washington State Pavilion and the United States Science Pavilion, now known as the Pacific Science Center, just to name a few) that mingle with newer additions such as the Frank Gehry-designed EMP Museum. Presiding over it all is, of course, is the Space Needle, a flying saucer-topped observation tower that's home to an observation deck, a slooowly rotating restaurant and a couple hundred out-of-towners at any given time.

In 2000, Seattle's most iconic and once-tallest structure — at 605-feet, it's not all that tall anymore, at least compared to the rest of Seattle's skyscraper-dominated skyline — received a $20 million top to bottom — or aircraft warning beacon to basement, rather — refurbishment. This is roughly the same amount it cost to erect the $4.5 million "Space Cage" back in 1962 in current dollars. On that note, the original $1 admission fee to hop aboard the zippy elevators up to the observation deck has jumped just a wee bit: an on-site ticket costs adults $21 a pop.

7. Unisphere — 1964-1965 New York World's Fair

The All-Nite Images [CC by 2.0]/flickr

Much like the Seattle World's Fair, the third itineration of the New York World's Fair, a Robert Moses-organized event that enjoyed April through October runs in both 1964 and 1965, was a space age-themed bonanza populated by swooping, modernist structures that might as well have been imported straight from Tomorrowland to Flushing Meadows-Corona Park in Queens (not a stretch considering the fair’s numerous Disney associations). Unlike the Seattle World’s Fair, few of these structures remain standing.

However, a couple of leftovers do remain. While the deteriorating ruins of Philip Johnson's New York State Pavilion and its abandoned observation towers are the most visible (and spooky), the Unisphere has fared much better over the years. A monumental globe — at 12 stories high, it's the “world’s largest world" — built from stainless steel and dedicated to "Man’s Achievements on a Shrinking Globe in an Expanding Universe," the Unisphere experienced a renaissance of sort in 1996 thanks to an appearance in the first "Men in Black" film in which it's destroyed by a rogue flying saucer commandeered by an extraterrestrial cockroach.

8. Habitat 67 — Expo 67, Montreal

meunierd/Shutterstock

A game-changer for Canada and the only world's fair that we know of to have a professional sports team named in its honor, Expo 67's motto — "Man and His World" — left a lasting legacy on the city of Montreal.

Built as a theme pavilion geared to showcase a new, experimental mode of housing that "modifies the 'single family dwelling' to exist concisely and effortless in the high density environment of a city," the dizzying concrete jumble on the banks of the St. Lawrence River otherwise known Habit 67 still stands strong as a landmark feat of architecture — "an icon of permanent modernity" — nearly 50 years later. Designed by Israel-born Canadian-American architect Moshe Safdie to offer a "fragment of paradise for everyone," this community-centric Brutalist housing complex is composed of 354 prefabricated modules stacked atop each other in numerous configurations like a madcap LEGO concoction come to life (yes, the plastic construction toys from Denmark did play an important role in Habitat 67's initial design). While Habitat 67 initially provided housing specifically for Expo 67, it's now composed of 146 highly coveted residences, some rental units, spread out across 12 floors. Each individual residence is housed in anywhere between one to five of the signature "cubes" depending on its size and layout.

9. The Biosphere — Expo 67, Montreal

leo gonzales [CC by 2.0]/flickr

Despite the political infighting and a pas parfait 6-month run, Expo 67 is regarded as the most successful international exposition of the 20th century. It's only fitting then that two remaining architectural landmarks left behind by Expo 67 both appear on our list.

Still looming over Ile Sainte-Hélène as the bubble-licious crown jewel of Montreal's Parc Jean-Drapeau, the United States Pavilion was one of the most well-attended — and polarizing — attractions at Expo 67. How typical of America to upstage Canada and during its first ever world's fair to boot! Polymath extraordinaire Buckminster Fuller is responsible for the pavilion's impossible-to-miss form, which takes the shape of a 20-story tall geodesic dome. The acrylic-skinned structure, which was partially destroyed by a fire in 1976 and reopened two decades later as the Biosphere environmental museum, is without a doubt the most famous geodesic dome in North America, second only to Spaceship Earth — you know, the golf ball-esque centerpiece (technically, a geodesic sphere) of Disney's Epcot theme park (a.k.a. Central Florida's Permanent World’s Fair).

10. Tower of the Americas — HemisFair '68, San Antonio

Nan Palmero [CC by 2.0]/flickr

The most modestly attended 1960s-era world expo, only 30 countries participated in San Antonio's HemisFair '68 — roughly half the number of countries that descended on Montreal the year prior. But whatever, the event birthed a benevolent dragon named H.R. Pufnstuf and that, in our book, is a huge deal.

Another huge deal, literally, to come out of HemisFair '68 was the Tower of the Americas, a 750-foot-tall observation tower (antenna included) that, up until the 1996 completion of Las Vegas's Stratosphere, was the tallest in America. It remains the tallest structure in the city of San Antonio. Subject to a public name-that-tower contest that officials hoped would help to quell early controversy surrounding the tower, rejected names include "The Purple Peeple Steeple" and the "Wineglass of Friendship." Much like its shorter older sis, the Space Needle, the Tower of the America's is still a skyline-dominating draw for tourists who flock to its observation deck and rotating restaurant for some truly knockout views (and a piece of Hot Chocolate Lava Cake).

11. Tower of the Sun — Expo '70, Osaka

m-louis .® [CC by 2.0]/flickr

It's hard to believe that a description-defying building that looks like this has experienced prolonged neglect and even threats of demolition in its post-expo afterlife.

Yet this was very much the case with Tower of the Sun, a colossal artwork designed by far-out sculptor Tarō Okamoto was the theme building for Expo '70 in Suita, Osaka, Japan. Spouting wings, clad with three distinct faces — the face on the rear looks into the past, the face on the steel-framed concrete building's mid-section represents the present and the face up top, which shot xenon laser beams out of its all-seeing eyes during the run of Expo '70, peers into the future — and towering 230 feet over Expo Commemoration Park, the Tower of the Sun has mercifully received much-needed TLC in recent years. Designed to represent the "infinite development of humankind and the power of life," the Tower of the Sun was once home to a tri-level exhibition space inside of its hollowed-out belly. Only recently have park officials begun permitting the general public to step inside of this weird and wonderful world’s fair leftover.

12. Sunsphere — 1982 World's Fair, Knoxville

Knox County Government [CC by 2.0]/flickr

Unlike the perpetually popular Space Needle and Tower of the Americas, Knoxville's Sunsphere observation tower, erected as the theme structure for the Cherry Coke-debuting 1982 World's Fair, has experienced a lonelier post-expo life. Ambitious redevelopment proposals have come and gone and the Sunsphere, one of only two remaining world's fair structures alongside the Tennessee Amphitheater, has remained largely "vacant and underutilized" for the past three decades.

Still, the 266-foot-tall "golden microphone" is a much-beloved Knoxville landmark and hasn't (yet) been converted into the storeroom for a wig emporium. In 2014, a revamped fourth-level observation deck reopened to the public, refreshingly sans admission fee. (It cost $2 to ride the elevator up during the World's Fair). The Sunsphere's fifth level eatery, once operated by Hardee's, is also back open as Icon, a swank farm-to-table restaurant and lounge serving up kale salads, ham hock tater tots and specialty cocktails.

13. Canada Place — Expo 86, Vancouver

Imogene Huxham [CC by 2.0]/flickr

Robot mascots. Depeche Mode concerts. Dramatic Princess Diana appearances. House-sized Swatch watches. Seriously, the 1986 World Exhibition on Transportation and Communication — or, simply, Expo 86 — couldn't get more 80s if it tried.

As evidenced by Montreal's Expo 67, Canada is a damned fine expo host and this British Columbian extravaganza, held nearly 20 years later after the country's inaugural expo, is no exception. A game-changer for Vancouver, the most lasting legacy left behind by Expo 86, aside from this song, is the Canada Pavilion itself, a sail-topped structure that dominates the city's waterfront. Now known as Canada Place, the 23-floor complex — "an inspiring national landmark that welcomes you to the Pacific Gateway" — is now home to the Vancouver Convention Centre, the Vancouver World Trade Centre, a high-end hotel and numerous other tenants and attractions. And if you've ever embarked on a cruise to Alaska, chances are you did it from this iconic Expo 86 remainder.

14. Lisbon Oceanarium — Expo '98, Lisbon

Carlos Caetano/Shutterstock

Like the Space Needle and the Tower of the Americas before it, Oceanário de Lisboa, the Lisbon Oceanarium, managed to seamlessly transition from world’s fair highlight to standalone attraction.

Designed and built to long outlive its 4-month run as the perpetually bottlenecked Oceans Pavilion during the oceans-themed Exposição Internacional de Lisboa de 1998, the Lisbon Oceanarium is the largest indoor aquarium in Europe and the top-ticketed tourist draw in all of Portugal. Divided into a quintet of oceanic habitats, top attractions include massive sunfish, nightmare-inducing spider crabs and playful sea otters. It's worth noting that the Lisbon Oceanarium, one of a handful of Expo '98 leftovers gracing Lisbon's Parque das Nações, isn't the only world-class aquarium to receive an expo debut. Others include the Civic Aquarium of Milan (1906's Milan International), the Renzo Piano-designed Aquarium of Genoa (Expo Columbo '92) and the freshwater-only Zaragoza River Aquarium (Expo 2008).

15. China Pavilion — Expo 2010, Shanghai

m00osfoto/Shutterstock

Usually large and lavish, the host country pavilions erected for many — but certainly not all — modern-day world expositions are very much non-ephemeral in nature. That is, they're built to stick around for the long haul, usually repurposed to serve another function after the expo itself has come to a close.

The China Pavilion, the impossible-to-miss "Oriental Crown" of Shanghai's record-shattering Expo 2010, is a fine example of the trend. Built as the largest national pavilion to grace a world's fair ever, this $220 million showstopper — the tallest, most expensive and flashiest of the pavilions, naturally — built in traditional dougong style reopened in 2012 as the China Art Museum, the largest art museum in all of Asia at a whopping 1,790,000 square feet. Not to be confused with the National Art Museum of China in Beijing, the inverted pyramid-shaped structure with a blazing red paint job is noted for its sustainable design elements including a photovoltaic array and rainwater-filtering gardens, both located on the structure's massive, multi-layered rooftop.