USS Philadelphia, a 1240-ton, 36-gun frigate, was the second vessel of the United States Navy to be named for the city of Philadelphia. Originally named City of Philadelphia, she was built in 1798–1799 for the United States government by residents of that city. Funding for her construction was raised by a drive that collected $100,000 in one week, in June 1798. She was designed by Josiah Fox and built by Samuel Humphreys, Nathaniel Hutton and John Delavue. Her carved work was done by William Rush of Philadelphia. She was laid down about November 14, 1798, launched on November 28, 1799, and commissioned on April 5, 1800, with Captain Stephen Decatur, Sr. in command. She was captured by Barbary pirates in Tripoli with William Bainbridge in command. Stephen Decatur led a raid that burned her down, preventing her use by the pirates.

Samuel Humphreys was a noted American naval architect and shipbuilder in the early 19th century. He served the United States Navy as the Chief Constructor for the Navy from 1826 to 1846.