Guild House, the Spring Garden Street apartment house designed by Robert Venturi, has just come through its first major renovation since it opened 43 years ago, and miraculously, no one laid a hand on the original chain-link fence or tried to pep up the color of the balcony railings.

True, the owners briefly contemplated upgrading the fence to wrought iron, but the heresy was quickly put down. There was another rocky moment when the painters accidentally swabbed over the "Guild House" sign with a coat of primer. The apartment house went sign-less for the entire winter before workers could re-create the Franklin Gothic letters.

What's astonishing is that no one called to complain about the missing sign during all those months. Is there any other architectural icon that could fly so far under the radar? But then, Guild House was designed to fade into the background.

Guild House may look like just an "ordinary" building - to use the favorite adjective of its creator - but it's actually an extraordinary one. It holds the distinction of being Philadelphia's most influential 20th-century building.

So when architects from Venturi, Scott Brown & Associates began a $10 million renovation two years ago, their goal was to make sure Guild House came out looking as plain as its old self. It does, only now it has double-glazed windows and central air conditioning. All the original, famously humble finishes, from the chain-link to the red brick, have been lovingly restored under the careful eye of project architect Heather Clark.

Not bad treatment for a building that, in 1966, was viewed as the scourge of modern architecture.

Times have certainly changed. Many of the radical notions that Venturi first expressed in Guild House are now received wisdom. The design is a staple of architectural curriculums. Philadelphia even listed Guild House on its historic register for the 40th anniversary.

Passing by the apartment house today, it might not seem like the sort of building that could start an argument - never mind launch a revolution. A quaint six stories, it looks as nonthreatening as the elderly residents who occupy its 90 subsidized apartments.

But to a generation of architects who devoted their lives to cloning stand-alone towers with identical ribbon windows, Guild House was the equivalent of an invitation to a duel. After all, Mies van der Rohe's Seagram Building, which set the standard for the International Style, was only eight years old when Guild House debuted.

The hard-core modernists were baffled by Venturi's overt historical references, like the huge arched window on the top floor and the childlike square windows. When he featured the design in his book Complexity and Contradiction, which was published the same year, Venturi boasted that he was mimicking the composition of the Chateau d'Anet, a 16th-century French palace. But instead of putting a statue of a noble stag on the roof, Venturi crowned Guild House with its 20th-century equivalent: a giant television antenna.

"Is this building a parody?" Progressive Architecture, the leading professional journal of the day, demanded huffily.

Philadelphia's powerful head planner, Edmund Bacon, was said to be appalled by the design. Even Ada Louise Huxtable, the influential New York critic, admitted to mixed feelings.

But she was sympathetic enough to Venturi's ideas to understand the reason for the outrage that greeted Guild House: "It's a slap in the face to the true believers" in modernism, she wrote.

They had banished history from architecture. Venturi put it back. At a time when the shape of a window was an ideological statement, substituting a square for a rectangle was a very big deal. Venturi's use of glazed white brick at the base, and a thin strip on the fifth floor, effectively gave Guild House the classical organization of a bottom, middle and top.

Actually, Guild House did more than just recognize that architecture had a past. The self-effacing apartment house, commissioned by the nonprofit Friends Neighborhood Rehabilitation Program, challenged the modernists' whole approach to city-building.

Unlike the other subsidized housing going up at the time, Guild House wasn't a tower in the park. It wasn't a long slab, either. It was a proudly urban building that came to the sidewalk and included side wings that stepped back to give its residents complex views of Philadelphia.

Venturi chose red brick for the exterior because he wanted Guild House to fit in with the other buildings at Seventh and Spring Garden, then lined with rowhouses. The irony, of course, is that city planners soon destroyed that context. Today, the east end of Spring Garden Street is a turbid collection of superblocks occupied by inward-facing commercial buildings.

Like so many of Venturi's buildings, Guild House is layered with multiple meanings. The huge granite column at the entrance was meant to give the building the nobility of a great palace. But its placement, at the exact centerpoint of the arched window, was also a loving nod to Frank Furness, who made a habit of splitting his arches with columns. Guild House's doors may be small, but no one can miss the entrance, as they do at the superblocks across the street. The chain-link fence, meanwhile, recalled the enclosures around great houses.

Then there's the sign. Purists considered it vulgar. Venturi loved the way the thick letters celebrated shop signs. It's also a reference to the sign atop Philadelphia's other 20th-century icon, the International Style PSFS building.

Venturi's influence wasn't entirely for the good. As less-talented architects appropriated similar historical elements, a kitsch-scape of pediments, gables, and arches flooded America's once-eclectic highway strips.

Venturi's jokes got him into other kinds of hot water. Some Philadelphians were offended by the gold, anodized antenna on the roof. They thought Venturi was making fun of the elderly for watching too much television. The antenna disappeared soon after Guild House opened and hasn't been seen since.

But how about this for the ultimate recognition: After 43 years, the Guild House's owners are considering spending $20,000 to buy a replacement.

Contact architecture critic
Inga Saffron at isaffron@phillynews.com.
or 215-854-2213.