The church of Sant' Agnese fuori le Mura (St Agnes Outside the Walls), which is built over the catacombs where St Agnes is buried, was founded by Pope Honorius I (r. 625-38).
At the back of the church is a narthex for catechumens. The nave is separated from the aisles by 14 ancient columns. There is a Matroneum above the aisles and the narthex, the earliest such feature to survive in a Roman basilica. The richly carved wooden ceiling was added by Pope Paul V (r. 1605-21) and restored in the middle of the 19th century. In the centre is St Agnes; the other two saints are St Cecilia and St Constantia.
The glory of the church is its apse. The glorious mosaics date back to the reign of Pope Honorius, while the baldacchino was created during the time of Pope Paul V (r. 1605-21).