Tivoli Cathedral (Italian: Duomo di Tivoli or Basilica Cattedrale di San Lorenzo Martire) is a Roman Catholic cathedral, dedicated to Saint Lawrence, in Tivoli, Lazio, Italy. It is the seat of the bishop of Tivoli.
According to a legend, it was built by Emperor Constantine after the Edict of Milan (313). The local tradition attributes the building of the church to Pope Simplicius (468-483), who was born at Tivoli. The Liber pontificalis, in the biography of Pope Leo III (795-816), contains the first reference to the "basilica beati martyris Laurentii sita infra civitatem Tyburtinam" ("basilica of the Blessed Martyr Lawrence in the town of Tivoli").
Whatever the exact date, the first church was built over the basilica in the forum of the Roman city of Tibur (1st century BC), whose apse can still be seen behind the one of the present building. This church was rebuilt in Romanesque style between the 11th and 12th centuries, and the bell tower belongs to this rebuilding.
The present cathedral, in Baroque style, was built by order of Cardinal Giulio Roma, bishop of Tivoli from 1634 to 1652. It has one nave with side chapels. It was consecrated on February 1, 1641, and completed with the portico in 1650. In 1747 the side door on the north was created, while the inside decoration dates from the early 19th century.
The west front of the church has a portico with three arches, and is flanked by the Romanesque bell tower, about 47 meters high. The interior was decorated by the Roman painter Angelo De Angelis in 1816: on the vault are paintings depicting The Glory of St. Lawrence, Faith and Religion, while in the apse are depicted four saints from Tivoli: Pope Simplicius and the martyrs Generosus, Symphorosa and Getulius. The altarpiece represents St Lawrence in front of the Judge, and was painted by Pietro Labruzzi.