Travertine is classified properly as a type of limestone although it is often referred to as a marble. It has long been used in both sculptural and architectural applications. In Italy, well-known travertine quarries exist in Tivoli and Guidonia Montecelio. The Guidonia quarry was one of the quarries where Gian Lorenzo Bernini selected material from which to build the Colonnade of St. Peter's Square in Rome (colonnato di Piazza S. Pietro) in 1656-1667. Michaelangelo also chose travertine as the material for the external ribs of the dome of St Peter's Basilica.
Travertine derives its name from the former town, known as Tibur in ancient Roman times. The ancient name for the stone was lapis tiburtinus, meaning tibur stone, which was gradually corrupted to travertino (travertine).