In the uppermost reaches of the Babilônia favela, Estrelas da Babilônia has a picturesque open-air setting with an unrivaled view of the mountains and sea, with the cityscape of Copacabana wedged between the two. It's a fun and welcoming spot, run by a Colombian-Belgian couple, with a lineup of live music, film screenings and other events. It's worth coming for the view alone.
At the time of research, however, Estrelas da Babilônia remained closed owing to the security situation (ongoing gun battles in the favela). Call ahead before making the trip up.