San Sisto Vecchio is a church in Rome, devoted to St. Pope Sixtus II. It was built in the 4th century, and is recorded as the Titulus Crescentianae, thus relating the church to some Crescentia, possibly a Roman woman who founded the church. According to tradition, the church was established by Pope Anastasius I (399-401).
The church houses the relics of St. Pope Sixtus II, transferred here from the Catacombs of St. Callixtus in the 6th century.
San Sisto was rebuilt in the early 13th century, by Pope Innocent III. The current church is the result of the restorations of Pope Benedict XIII (18th century), which left only the bell tower and the apse from the medieval church.
A 13th century fresco cycle depicting the Scenes from the New Testament and the Apocrypha is conserved.
In the nearby monastery, which belongs to the Church, Dominican nuns are living.