The present church of San Martino ai Monti dates from the Carolingian era, but a 3rd century colonnaded structure has been found under and next to a later church. Most of the pics are shot from under the floor level.
The Basilica was founded by Sylvester I on land donated by a member of the Equitii family (hence the name Titulus Equitii) in the 4th century. At the beginning it was an oratory dedicated to all the martyrs. It is known that a preparatory meeting of the First Council of Nicaea was held here in 324.