Imagine a tower more than 40 stories high, sparkling as the sun catches a hundred thousand pieces of colorful cut glass. Imagine this tower at night, lit by dozens of spotlights as its gown of glass shimmies in the wind for a gaping audience beneath -- an audience that was only just starting to have access to electricity. Imagine the promise this vision held, the way it pointed your city towards the future.

San Francisco’s merchant and civic leaders poured their hearts into the 1915 Panama Pacific International Exposition, or PPIE. This world’s fair was ostensibly celebrating the recent completion of the Panama Canal -- but really, this was the city’s chance to show the world that it was back.

The city wrestled 635 acres from the swampy tidal marsh on the northern end of the city in what’s now the Marina. Builders from 28 states and territories and 21 nations constructed the lavish halls that would hold the exhibitions. By the time the fair opened on February 20, 1915, few traces of the wild marsh remained. Instead, visitors strolled through opulent gardens, past fountains and exquisite statues, and traversed 47 miles of walkways between the exhibit halls.

The exhibitions, themselves, held endless wonders: The Palace of Machinery was so huge that it was the world’s first building to have a plane fly through it.

At the Southern Pacific Railroad exhibit you could walk through some of California’s giant redwood trees. You could watch sumo wrestling, or hear the clang of a working Model T assembly line. You could listen in on the country’s very first transcontinental phone call, or watch a machine milk a cow.

The goal of the fair, so says the official history, was to create, “a microcosm so nearly complete that if all the world were destroyed except the 635 acres of land within the Exposition gates, the material basis of the life of today could have been reproduced from the exemplifications of the arts, inventions and industries there exhibited."

San Francisco on the world stage -- the good and the bad

“It's so quintessentially San Francisco,” says Laura Ackley, a local historian who recently published a book about the PPIE. “Of course no sane city would decide in the face of disaster that what they're going to do is throw a gigantic party and invite the world, but of course that's exactly what San Francisco did.”

The city tried to use the PPIE to position itself as a center of excitement and modern ideas. But it didn’t always succeed. There were at least four facades, though they changed over the course of the fair, that depicted African-Americans as offensive caricatures. Ackley says all world’s fairs had similar issues -- they reflected mainstream culture of the time, both good and bad.

San Francisco’s fair was unique not for its flaws, but for its successes.

“It was technological, it was modern,” she says. “The Bay Area has always wanted to position itself as a place of innovation, and I think that is absolutely still true today.”

Remembering the fair today

For all of its decadence, the fair only lasted about nine months. All of the beautiful buildings were flimsily made of plaster, and in the weeks and months after the fair, almost all of them came down. A few lonely ones remained, supposedly because the fair’s architect, Edward Bennett, thought that every great city should have a few ruins. The only building that remained onsite was Bernard Maybeck’s Palace of Fine Arts.

In the 1960s, The Palace of Fine Arts was totally reconstructed, and today, it’s the neighborhood’s only remaining trace of the PPIE. A fitting place to kick off a centennial celebration.

Among the many innovations visitors could witness at the original fair, the one that stirred up the most excitement was a little Hawaiian instrument called the ukulele. To give you an idea: Henry Ford, of Ford Motors, loved the music so much that he convinced the Hawaiian ukulele band who played at the fair to move to Detroit and play for Ford employees. Today, people are just as enthusiastic -- hundreds show up to play under the rotunda for a “uke-a-thon.”

Many of the people here are deeply connected to the PPIE. Donna Ewald Huggins is the mayor’s liaison for the centennial exposition and has been collecting items from the PPIE for over 40 years. She has the PPIE in her blood: her grandparents fell in love under the rotunda here while visiting the fair, and the rest is history that Huggins has spent her whole life collecting. She actually met her fiancée through their mutual fascination with PPIE. He proposed on the 100th anniversary, with a ring that is a duplicate of one from the Tower of Jewels.

Huggins has set up a portion of her collection in a glass case in a corner of the room. People crowd around to see the hat pins, button hooks, and souvenir shoes on display. And there are lots of people who want to show her parts of their own collections.

Several enthusiasts come dressed up as figures who attended the fair in 1915. Thomas Edison and San Francisco mayor Jim Rolf show up, along with some lesser known figures. Carol Jensen, a local historian, has dressed up as Mae Mead, the Contra Costa County chairwoman for the woman’s board at the time of the PPIE. Her mother visited the fair 100 years ago, and told Carol about seeing the rotunda lit up.

“I stood outside and I thought, 'One hundred years ago, my mother saw this,'” Carol says. “I get a little emotional just thinking about it.”

One hundred years later, the Palace of Fine Arts will once again host crowds of visitors eager to see the latest technologies on display -- this time, at the new Innovation Hangar. Instead of Ford’s Model Ts or milking machines, you’ll see virtual reality games or workout clothes that can sense your heart rate. Inside, you’re immersed in the future -- but walk outside and look at the rotunda, and it’s not so hard to feel the wonder of the past.