It is cut content in Mafia II. It consists of what appears to be Vito's first home in Empire Bay where his family lived after immigrating from Sicily in 1932. You can see the apartment in the game's opening cutscene. In game you can see the front of the apartment as well as an unusable garage to the lower left.
While not usable in game, it is marked on the game map that came with physical copies of the game with the standard home icon of a key inside a green circle. An unused mission screen from the Joe's Adventures DLC found within the game's files shows Joe and Antonio Balsamo inside the apartment.