This small museum exists for one thing: Diego Rivera's mural "Dream of a Sunday Afternoon in the Alameda Central." Painted in 1947 for the dining room of the Hotel del Prado on the south side of the Alameda, the mural shows a tightly packed promenade scene with Frida Kahlo, Posada's skeleton Catrina, and Rivera himself as a small boy holding her hand — alongside hundreds of historical figures from across Mexican history.
The hotel was so badly damaged in the 1985 earthquake that it had to be demolished, but the mural was carefully cut out and moved to this purpose-built single-room museum at the western edge of the Alameda. The viewing space lets you see the whole painting at the correct distance. Allow 30 minutes.