Chega de saudade is a magical song. Sing this in a room with brazilians, and everyone starts singing along quietly. It is like their informal national anthem.
This is the song that marks the start of the bossa nova movement in full force, when it was recorded by João Gilberto in 1958. The beautiful music is by Tom Jobim, the poetic lyrics by Vinícius de Moraes. Those three are the key persons of the early days.
Yet this song is not your typical bossa nova. The structure is quite unusual. The fascinating melody goes all over the place, and sounds like a sophisticated and subtle samba melody.
One more thing: to me, this is the most beautiful song ever written.
Here is my own take on Chega de saudade.