Philadelphia Sketch Club, America's oldest continuously-operating club for artists, was founded in 1860. Since its founding by six students of the Pennsylvania Academy of the Fine Arts (PAFA), Philadelphia Sketch Club has offered art classes, mounted exhibitions, and given artists the opportunity to socialize and network with each other. In over 150 years, the Club has acquired quite a breathtaking collection of works of art. Its walls are paved with paintings by past members--a memorable series of member portraits by Thomas Anshutz rings the library--but art isn't just on the walls, it is everywhere. 
The light fixtures were wrought by an artisan blacksmith; the windows are stained glass; in the rathskellar, the very beams are carved with illustrations. The tone inside the Philadelphia Sketch Club is electric; it positively breathes artistic inspiration. Indeed, the creative energy of the Club has been upheld by the generations of renowned artists who have walked its halls: Thomas Eakins, N. C. Wyeth, Alexey Brodovitch, R. Tait McKenzie, Howard Chandler Christy, and Samuel Yellin, to name just a few.
The Philadelphia Sketch Club maintains its own archives, the importance of which was recognized by the Smithsonian Archives of American Art when they microfilmed selections from the collection in the 1990s. Large chunks of material were skipped over by the microfilmer, however, so you'll have to come to the Philadelphia Sketch Club to see the entirety of their records. Spanning from 1860 to present, the collection includes minute books, treasurer's reports, ledgers, receipts, dues books, membership applications, exhibition planning materials and catalogs, photographs, and many other records of the organization. For me, the highlight of the collection was a box of member-made Christmas cards, circa 1920-2004. The Philadelphia Sketch Club archives is a great place to learn more about your favorite artist, or to inspire the artist in you!