Athena is the Athenaeum's library catalog. Use it for finding books and trade materials. Some architectural drawings and photographic collections are cataloged in Athena, but these are more easily searched in PAB.
The Philadelphia Architects & Buildings Project is a cooperative effort between the Athenaeum, The University of Pennsylvania, The Philadelphia Historical Commission, and the Pennsylvania Historical & Museum Commission. It contains information on buildings, architects, and the architectural collections of over 30 local institutions. Use PAB to find architectural drawings and photographs.
This link will take you directly to the Athenaeum's collection list in the PAB database. It is best used for browsing within a particular collection.
These databases are only available from computers at The Athenaeum.