The Athenaeum is a must-see for architecture and design enthusiasts, or anyone looking for a glimpse into the finest in 19th-century living. Established as a research library in 1814, its first member was renowned architect William Strickland in 1820.

Strickland’s 1839 proposal for a building to house the library on Washington Square was the first drawing acquired by the Athenaeum. It now contains more than a million books, architectural drawings, photographs, and manuscripts representing the work of more than 1,000 American architects, and is considered the premier landmark devoted to American architecture 1800–1945.

The 1st-floor gallery is open to the public, but you’ll need to make an appointment in advance to tour other areas.

Designed by architect John Notman in 1845, the building is one of Philadelphia’s first brownstones. The relatively simple exterior belies the ornate reading rooms and 24-foot ceilings inside.