On the east side of Washington Square, a Renaissance Revival building has kept watch over the park since the mid-19th century. Gas lamps on posts flank its modest entrance, where brass plaques (discreetly) announce "The Athenaeum." It would look at home on an Italian piazza.

Kevin Ryan, a frequent passerby, has long wondered what's inside.

"It appears to be a museum of some sort," he said one recent afternoon.

Dog walker Meg Kennelly also was perplexed. She walks Duke, a yellow Lab, past the brownstone building every day.

"I've asked a few people," she said, "and they don't know."

Now she does: The object of Ryan's and her curiosity, the Athenaeum, contains Philadelphia's last remaining subscription library, as well as a world-class architecture archive, and an art gallery.

"I hope no one will confuse us with a Greek restaurant," the museum's director, Sandra Tatman, says with a smile.

Tatman, who took over directorship of the library in late 2007, is the first woman to lead the institution in its 196-year history. With it bicentennial approaching in 2014, she hopes to take it into the digital age with its old-world charm intact.

In the era before public libraries, subscription libraries were the norm. Because 18th-century books were expensive, Benjamin Franklin surmised that if readers pooled resources, they might share costs, socialize, and debate about what they read. In 1731, he formed the Library Company of Philadelphia, where the public could read the books but only fee-paying members could take them out.

More subscription libraries would follow, among them the Athenaeum. It spent its first three decades renting space in nearby Philosophical Hall before its members commissioned Scotsman John Notman to design a new home in 1845. In addition to being one of the nation's first Renaissance Revival buildings, the Athenaeum was also one of the city's first brownstones, Notman's cost-cutting alternative to marble.

Said Tatman, "He knew we were always going to be a nonprofit and so he designed the first floor as rental space." (She noted that it was her predecessor, Roger Moss, who during his 40-year tenure converted that rental space into offices, a boardroom, a digital scanning studio, and a gallery, and who oversaw renovation of the second-floor reading and research rooms.)

The hushed Athenaeum vibe is decidedly clubby; the subdued palette and the furnishings' Anglo overtones nod to old Philadelphia. Just beyond the glass front doors is the gallery, where "American Place," the 75th-anniversary show of the Historic American Buildings Survey, runs through July 30.

The Historic American Buildings Survey, part of the Works Progress Administration, continues to record the nation's architectural landscape with drawings and photographs. Thus it is somewhat reflective of the Athenaeum's own collection, which includes 250,000 architectural drawings and 300,000 photos.

Just outside the gallery, a large spiral staircase leads up to the reading and research rooms. Natural light pours from the top of the stairs and is plentiful throughout - which may help explain why the library did not abandon gas lighting until 1923.

In the reading room, painted pine Corinthian columns flank two tiered alcoves filled with general-interest books behind leaded glass doors. Subscribers' tastes dictate the room's collection: Mystery, biography, history abound; vampires, sci-fi, and horror are harder to come by. The library has 100,000 books, 10,000 of them rare.

Across the hall, the research room is austere by comparison, though equally elegant. It was a periodical room in the 19th century, when the large-format newspapers of the day required substantial tables. Researchers now use the tables to accommodate oversized architectural drawings. (Among the Athenaeum's treasures: Thomas U. Walter's original drawings of Girard College and the dome of the U.S. Capitol.)

Access to these intellectual luxuries can be had for $75 a year for associate membership (ages 18 to 35), and $200 for subscribers - not a bad deal when compared to a gym membership. Tatman described the semi-open-door policy as welcoming (by appointment) to anyone who wants to do research, tour the building, view the gallery, or hear lectures.

"But if you want to borrow a book, then you must be a subscriber," she said.

There are ways, with a little effort, to gain free access. The library has hundreds of thousands of photographs and tens of thousands of books on art, printmaking, photography, architecture, and landscape design. Search the collections at www.philaathenaeum.org, compile a request, and call the library to make an appointment.

At the top of the Athenaeum heap are the shareholders (initial $500 fee, $125 annual dues), who can attend events, vote at annual meetings, and become members of the board of governors.

To be a shareholder, you must have a letter of recommendation from a current shareholder. Of 1,600 slots, 1,500 are filled; some family memberships have been handed down for generations. Truly fastidious newcomers seek the lowest-numbered shares available, i.e. the oldest.

Tatman acknowledged that the Athenaeum was sometimes slow to change, adding, "We always looked at the Library Company to see what they were doing."

John Van Horne, the Library Company's director, said, "We were the first" subscription library. "We started out that way. The Athenaeum has maintained that orientation, but we have evolved," shedding its original identity for that of a research library. Shares are still available, but Van Horne said they didn't come with many perks. Anyone can purchase a $200 share without a reference.

While the Library Company had female members as far back as 1769, the Athenaeum barred them until a share was issued to Mrs. Howard W. Lewis in 1857. In 1929, a lone woman, Mrs. Arthur H. Lea, joined the board. Yet when Tatman entered the museum field - she was an Athenaeum intern, and later its curator - she frequently was the only woman in the room at meetings; now, at 65, she often still is.

"Art history is still dominated by women as undergraduates. But they don't always get their graduates and doctorates," she said. Still, the former university professor said, she's cheered by the fact that more are coming into directorships, and that more female academics are using the archives.

One area in which the Athenaeum has been cutting-edge is digital technology. Its superb online resources include the American Architects and Buildings database and the Greater Philadelphia Geohistory Network, excellent databases coordinated with local and national institutions.

The library's Regional Digital Imaging Center can scan books and paintings without the danger of cracked bindings or harmful lights damaging the art, and can capture documents up to 48 by 72 inches (larger with the aid of Photoshop). Notable documents that have been scanned are the Treaty of Paris, the Bill of Rights, and the Emancipation Proclamation.

Local artists make use of the facility to scan their artwork. Anyone can peruse the museum's archives, find an etching, and have it blown up to be framed ($75 for a large-format color print). The revenue supports programs and future gallery exhibits.

As the Athenaeum alternately inches and bounds toward its third century, some continue to pine for bygone days and rituals. One that lasted through the 1990s was the shareholders-only cut crystal decanter of sherry in the main reading room.

Here Tatman draws the line.

"We're not bringing the sherry back," she said.

View additional photographs and a video with Sandra Tatman at www.philly.com/ seeAthenaeum.


The Athenaeum

The Athenaeum of Philadelphia is at 219 S. Sixth St.

Hours: 9 a.m. to 5 p.m. Monday to Friday. Search databases, learn about services, and become a member at www.philaathenaeum.org. To make an appointment to view a book, document, drawing, or photograph, call 215-925-2688. EndText

Contact staff writer Tom Stoelker at 215-854-2931 or tstoelker@phillynews.com.