309 South Broad Street (Sigma Sound)

Philadelphia invented something. In the early 1970s, at 309 South Broad Street, producers Kenny Gamble and Leon Huff built Sigma Sound Studios and created a genre: Philadelphia Soul, lush strings, smooth grooves, political consciousness wrapped in music that the whole world wanted to hear. The O’Jays, Harold Melvin & the Blue Notes, Patti LaBelle, Teddy Pendergrass, Lou Rawls, the Sound of Philadelphia. The building still stands. The legacy runs through every R&B and hip-hop record made in the decades since.