Praia da Ipanema is the other famous beach in Rio de Janeiro. The beach became famous worldwide thanks to the song "Garota da Ipanema" (Girl from Ipanema), composed in 1962 by Antonio Carlos Jobim, with lyrics by Vinícius de Moraes, and originally sung in Portuguese by João Gilberto.
You do have to go to Ipanema to understand the "praia" culture (beach culture). So take your sunscreen and your bikini or speedo, and enjoy the show.