According to tradition, the church was consecrated in 969. The interior floor plan consists of three naves outlined by the columns with ancient Roman marble and granite capitals. The counter-façade and the central nave are decorated by Aliense, a pupil of Tintoretto (1592). Among other works of art, it hosts masterpieces by Eusebio da San Giorgio, Pietro Perugino, Sassoferrato, Vasari, Conca, Cerrini, Wicar. Noteworthy are the wooden choir (1523-35), the large painted baldachin and the main altar. The sacristy boasts a lovely Deruta terracotta floor (1563-64). The elegant bell-tower, erected above the remains of an ancient Roman monument, was restored to Gothic forms in 1347 and completed by Bernardo Rossellino in 1463.