William Strickland's Greek Revival masterpiece at 420 Chestnut Street is one of the most beautiful buildings in Philadelphia — a white marble temple with a colonnaded portico based on the Parthenon, built in 1824 to house the Second Bank of the United States. The Bank was the center of one of the defining political battles of early American history: Hamilton's Federalist vision of centralized finance against Jacksonian democracy's suspicion of concentrated power. Jackson won, vetoed the re-charter, and the Bank died in 1836. The building survived.
The National Park Service now operates it as a portrait gallery, with paintings by Charles Willson Peale and other colonial-era artists depicting the founding generation — many of them painted from life. The galleries are free to enter and rarely crowded, which makes them one of the best-kept secrets in the historic district. The building itself is worth the visit: the central banking hall, with its barrel-vaulted ceiling and cast-iron teller cages, gives a sense of what financial architecture looked like when the republic was still new enough to want to impress itself.