San Giovanni in Conca is the crypt of the former basilica in the center of Piazza Missori in Milan. It is the only one example of a Romanesque crypt preserved until modern times. Above the crypt are the remains of an ancient apse with arcades. Archaeological finds allow to illustrate the history of the old church in this place. The remains were placed in the Sforza Castle. The most important exhibits are two sculptures from the 11th century depicting the Annunciation, tomb monuments and Romanesque capitals and frescoes dated to the 14th century.
The Basilica of San Giovanni in Conca dates from the 4th century and was in a residential area of the ancient city. Remains of the mosaic surface of this original building are now in the Archaeological Museum of Milan. The church was finally demolished in 1949.