Clube de Futebol Os Belenenses was founded on 23 September 1919 in the Belem district of Lisbon and plays in blue and white at the Estadio do Restelo, which the club owns. It is one of only a handful of clubs to have won the Portuguese championship, taking the 1945-46 title, and has lifted the Taca de Portugal three times.

In 2018 the professional arm split away and later became B-SAD, leaving the historic club to restart in the amateur ranks and work its way back up the divisions.