Certain buildings or certain blocks of San Francisco streets have a way of standing out to the architectural observer because they don’t quite fit with the eras of design we most associate with the city.

Jackson Street, for instance, near Jackson Square, with its pre-1900 mercantile architecture looks more like New York’s Soho than anywhere in SF, due to the fact that it was saved from burning during the 1906 earthquake (thanks to a certain whiskey warehouse in the neighborhood). Or the original adobe Mission Dolores and the Tanforan Cottages on Dolores Street, which predate much of the Mission District.

But the glass-walled, seven-story retail and office building at 130 Sutter, known as the Hallidie Building, completed in 1918, is an exception among the exceptional. This is, in part, because its architect, Willis Polk, pushed himself late in his career to design something unlike anything else that had been built in this city, let alone anywhere in the United States.

“I’ve turned a building wrong side out.”

Commercial buildings with lightweight, sheer glass curtain walls—something that would later be a common feature of skyscrapers of soaring heights—were not yet in fashion in 1903, even though a couple of examples had appeared in Europe. As Kenneth Frampton and Yukio Futagawa write in Modern Architecture: 1851-1945, “Natural light, budget limitations, and a desire to facilitate erection, were all to influence Polk’s decision to produce an all-glass facade,” which “exploit[ed] the cantilevering capacity of reinforced concrete to its fullest.”

Many architecture historians consider Hallidie groundbreaking, with some christening it the most important modern building in San Francisco. Frampton and Futagawa call it a building of “extraordinary precision and lightness” and “the unique triumph of Polk’s career.”

While the juxtaposition of the building’s lacy, gold-painted iron ornaments—which have echoes in the gold crowns atop the street lamps that went up downtown in this same era, between 1915 and 1918—and the uninterrupted grid of glass is striking in its oddness, it’s the glass curtain itself that made this building unique for 1918. The window wall is supported by brackets projecting from each concrete floor platform attached to steel mullions so that the surface floats in front of the structure, not unlike the way curtain walls are constructed today.

Nothing that Polk had designed in San Francisco, particularly in the booming post-quake decade prior to this commission, showed any indication that he had a flair for something so innovative and sleek. Polk worked mostly in the neo-classical and Beaux Arts styles of the most popular firms of his day. He collaborated personally with famed New York firm McKim, Mead and White, as well as Chicago architect Daniel Burnham, becoming the head of Burnham’s West Coast office in 1903—one year after the completion of Burnham’s singular triumph, the 20-story Flatiron Building in New York.

Just look at two of the most significant projects Polk worked on during his decade representing D.H. Burnham and Company: the Merchants Exchange Building (completed in 1903 but heavily reconstructed following the 1906 earthquake with the help of a young Julia Morgan), with its heavy columned facade; and the 21-story Hobart Building at Market and Montgomery, completed in 1914, in which Polk applied layers of Burnham-esque, Beaux-Arts cornice details to what was at the time the city’s second-tallest skyscraper.

Now look at the Hallidie Building and imagine that Polk receives this commission just two years later, in 1916, on the eve of what would be the World War I-related construction decline marking the end of his storied career. He had overseen the 1915 Panama-Pacific International Exposition (and he was ultimately influential in making sure that Bernard Maybeck’s iconic Palace of Fine Arts was preserved and not demolished), and he was commissioned by the University of California to build an investment property in the bustling Financial District, at 130 Sutter. The budget was less than $250,000, a moderate sum for the time, and construction took just six months in 1917.

Topped with Gothic flourishes and trimmed with period ornament that likely matched up with the building’s neighbors at the time, the Hallidie building was an early glimpse into a glassier future that wouldn’t become commonplace for decades. You can see how Polk ingeniously grappled with what would become a common problem architects would face in the decades ahead: how to pack as much office space and natural light as possible into a given square footage without relying on the traditional, heavy stonework associated with shorter, squatter buildings. Cities were getting taller, and not every big building needed look like a Greek temple or modified cathedral.

The thinking and motives behind Polk’s innovation with the curtain wall remain a mystery with which he went to the grave (just six years later, in 1924, at age 56), and it’s possible that he was inspired by the work of Walter Gropius in Germany, whose Fagus Factory was completed a few years earlier, in 1911. Anecdotally, Polk was described as a difficult and “obnoxious” man who perhaps wanted to take credit for an idea that wasn’t entirely his own, though he may indeed have, on his own, come to the same foregone conclusion that Gropius, Mies van der Rohe, and other modernists would about the direction of commercial architecture.

Architectural historian Henry-Russell Hitchcock, in his book Architecture: Nineteenth and Twentieth Centuries, concluded that Polk could “certainly” not have been influenced by Gropius, and that the Hallidie building is indeed the first “true” curtain wall because, unlike the Fagus Factory, it’s uninterrupted horizontally.

As professor emeritus at San Francisco State University, Marvin Nathan wrote, in a 1987 piece for the California Historical Courier, that Polk hinted that he wanted to give SF a nod to London’s famed Crystal Palace, and perhaps he was pushed by the client to provide “more light and warmth in San Francisco’s changeable climate than conventional structures would allow.” Polk himself told the San Francisco Examiner that he’d nicknamed it the Munchausen Building, after the story of Baron Munchausen pulling a bear “wrong side out” with his bare hands.

“And that’s what I’ve done,” said Polk. “I’ve turned a building wrong side out.”

Polk also creatively addressed another aesthetic problem facing designers of tall buildings: fire safety. He added fire escapes that are decorative rather than utilitarian and ugly, with small, rounded balconies strung vertically together along either flank of the Hallidie Building by dainty ladder chains.

It’s notable that Polk’s inventiveness in his curtain-wall design would be forever paired with another innovator, Andrew Hallidie, the SF man credited with inventing the cable car, in whose honor the University of California would name the building (nearly six decades before Hallidie Plaza was christened at the base of Powell Street). Hallidie looked at this hilly city’s problem of horse-drawn streetcars and came up with a steam-powered solution in 1873 using thick steel cables moving between the street car’s tracks, so that horses didn’t have to fall victim to our steepest streets any longer.

(Footnote: Hallidie wrote evocatively in an 1871 report to the Mechanics’ Institute: “I was largely induced to think over the matter from seeing the difficulty and pain the horses experienced in hauling the cars up Jackson Street, from Kearny to Stockton Street, on which street four or five horses were needed for the purpose—the driving being accompanied by the free use of the whip and voice, and occasionally by the horses falling and being dragged down the hill on their sides, by the car loaded with passengers sliding on its track.”)

It’s difficult to see Willis Polk’s uninterrupted, elegant glass facade through the eyes of someone in 1918. One has to imagine a streetscape that was all columns, terracotta, and brick—a downtown mostly resembling the Flood Building and the Hobart Building, dotted with diminutive, three-story street-fronts like you find still on Montgomery and Kearny. As Nathan tells us, locals at the time dubbed the Hallidie Building “the frontless building,” “the daylight building,” and “the camouflage building.”

Architectural Record declared Polk a “pioneer” in 1918, and it seems that Polk imagined his building would immediately inspire others to imitate him.

But it would be decades before the era of sheer glass cliffs would become the dominant mode of office towers everywhere; even in SF we’ve had few prominent examples of the caliber of Boston’s I.M. Pei-designed John Hancock Tower, or Chicago’s Willis Tower, but 181 Fremont is a handsome new addition in this category. Mies van der Rohe’s Seagram Building in New York City is often considered the game-changer for modern, glass-walled office towers, but that wouldn’t be completed until 1958, 40 years after Polk’s seven-story masterpiece on the West Coast.

In 2013, a team of local preservation architects led by McGinnis Chen Associates and including Page and Turnbull oversaw the historic restoration of the Hallidie Building, which revived its original blue-and-gold color scheme—chosen for the colors of the original client, the University of California. They returned the deteriorating ornamental metal work to its original glory, replaced all the glass, and made repairs to the weather-damaged curtain wall, giving new life to this landmark.

In his book Twentieth Century Architecture: A Visual History, Dennis Sharp calls the Hallidie Building “one of the finest and most uncharacteristic facades to be erected on the west coast in the late 1910s.” Indeed, it only barely resembles some of the commercial architecture of its era in any U.S. city, much of which doesn’t even exist anymore.

Polk could not have known, though perhaps he hoped, that the Hallidie Building would one day be a common feature of architecture school curricula. “The transparency and delicacy is amazing,” says architect Craig Hartman, a partner at Skidmore, Owings and Merrill. As he told the San Francisco Chronicle’s John King in this 2013 piece, shortly after the restoration, “My first visit to San Francisco this was one of the two buildings I made it a point to see the afternoon I arrived.”

One year after the completion of the Hallidie Building, in 1919, Walter Gropius would found the Bauhaus School, and he would later design the school’s main building in Dessau with its iconic three-story curtain wall in 1924—probably the most similar curtain-wall example to arrive after Polk’s design.

The Hallidie Building is No. 37 in the list of San Francisco’s landmarks, and among Willis Polk’s many contributions to the city’s architecture, it’s unarguably the most important. So much so that it currently houses the San Francisco chapter of the American Institute of Architects.

You can easily step inside because there’s a U.S. Post Office on the ground level, though not much of the original interior remains. For the best view of the Hallidie Building, head into the Crocker Galleria across the street, and climb up to the second mezzanine.

And remember to tell your New York and Chicago friends that while San Francisco may not have invented the skyscraper, it was an SF architect who foresaw the era of the sheer-glass office tower.