You could argue that Philadelphia already has an architecture museum: itself. The city boasts an architectural lineage longer and more varied than that of almost any other place in America, ranging from the Lilliputian colonial-era houses along Elfreth's Alley to the gargantuan, newly minted Comcast Center, the country's tallest green skyscraper.

But wouldn't it be nice if you could survey the full spectrum of the city's building history all in one convenient spot?

With the opening last week of the new Center for Architecture at 12th and Arch Streets, Philadelphia now has the beginnings of just such a place. Created by the local chapter of the American Institute of Architects, the center combines the AIA's administrative offices and its popular bookstore with a group of meeting rooms and a small, but easily expandable, exhibit space.

Galleries devoted to architecture are well established in New York, Chicago and San Francisco. But despite being the second oldest AIA chapter in the country, founded in 1869, Philadelphia has lacked its own showplace. One reason is that the chapter had been ensconced for almost 80 years in high-rise offices built with the profession in mind, the Architects Building at 17th and Sansom Streets. Designed just before the 1929 stock-market crash by a committee of the city's most prominent architects, including Paul Philippe Cret, the building offered a convenient, if low-visibility, home.

In 1976, the architects enlarged their profile a bit by opening a bookstore in the tiny corner lot. Because space was at a premium, the rotating exhibits were limited to a single display window.

The chance to open a real gallery finally came in 2006, when the owners of the Architects Building announced they were converting the slim art deco tower to a boutique hotel for the Kimpton chain, forcing the AIA to search for new space.

The organization soon understood that it had been priced out of its neighborhood, which has become Center City's premier shopping and office district. John Claypool, the chapter's executive director, looked at about 50 locations before buying a ground-floor commercial condo space at 1218 Arch St., the historic, classical revival manufacturing loft built in 1902 for Young, Smyth, Field & Co.

Though the new address is slightly outside the city's dense retail heart, the location is steps from the Convention Center and the Reading Terminal Market. When the Fabric Workshop debuts its new gallery space July 14, there will the nucleus of a virtual arts district - a dramatic turnaround for a block that seemed impervious during the last 15 years to the economic impact of the convention business.

The AIA's new center gives the organization more room for exhibits now, and the opportunity to expand later into a large basement. The street-level space also offers increased visibility for the bookstore and the gallery.

Having settled on a new home, there was then the delicate matter of finding the right architect to renovate it. The AIA organized a charette to solicit ideas. In the end, the space was designed in the same collective way as the Architects Building.

Design-by-committee rarely results in good work. And this time the committee had 1,400 professionals looking over its shoulder. But Brett Webber, who provided the design for the pivoting doors that separate the shop from the main conference room, says it was soon apparent that there was only one logical way to lay out the space: bookstore in front, meeting rooms in the middle, offices in the back, and a linear gallery along the side to connect them all. KlingStubbins contributed all the construction drawings.

Maybe because it's a group effort, the design is quite revealing about Philadelphia's current architectural preferences. The style of the space is deeply influenced by the city's industrial past. It's not just that the space was once a stockings factory. The architects took pains to highlight original details such as the triple set of leaded clerestory windows, rough brick walls and worn maple floors.

The new design elements are all frugal, functional and beautifully crafted, especially Webber's steel-and-mesh pivot doors, which are copies of the ones he created with fabricator Warren Holtzman for his own office. Instead of preening gestures, the designers allow the high, airy space to speak for itself. (Maybe too much, in fact. There could be a sign directing visitors to the gallery.)

Since the center is meant as a demonstration project, it was designed to be environmentally responsible. Besides the efficient ventilation systems and lights, the AIA persuaded manufacturers such as Knoll to donate slightly used furniture. Students at the AIA-sponsored Charter High School for Architecture and Design built the clever free-standing shelves. The only "frivolity," Claypool notes, is a group of hanging lights shaped like classic incandescent bulbs. The joke is that there are energy-saving LEDs inside.

With its attractive displays, the AIA bookstore has always been a good way to lure civilians and raise the public's design consciousness. Simple anecdotal evidence suggests that interest in architecture has never been higher, even as the quality of everyday buildings is falling to new lows.

It's interesting that the Netherlands, which created a comprehensive architecture museum in Rotterdam in 1993, has since become a hotbed of architectural innovation. Could there be a connection?

A real architecture museum that presented a timeline of Philadelphia's style changes could help us understand our city in a new way. An expanded AIA gallery can be that museum.

The more chances people have to see images and models of high-quality, contemporary architecture, the more literate and discerning they will be about their built environment.

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