For a bit of revolutionary history I would recommend paying a visit to Plaza de la Revolución ("Revolution Square").
The square is famous for being the centre point for many political rallies held by Fidel Castro and other Cuban political figures.
There you will find the José Martí Memorial, the National Library, many government ministries, and other buildings. Opposite the memorial on the far side of the square is the big and famous Che Guevara image with the slogan 'Hasta la Vict...