In the sixth century, Pope Gregory I built a monastery, where he lived for a long time, and in 575 a small church dedicated to St. Andrew, hence the name "St. Andrew's Monastery". The current appearance of the Church is conferred by Giovanni Battista Soria in 1629; while Francesco Ferrari (1725-1734) has designed the interior. The Church is reached by a long stairway; the facade above a colonnaded courtyard overlooked by the Church itself, with a second side. The porch is home to several tombs. The plant is typical of a basilica, with a nave divided from the aisles by ten ancient granite columns and pillars. The interior has three naves, with a deep presbytery. The cosmatesco floor is the thirteenth century; the ceiling of the nave is decorated with a fresco painted in 1727 by Placido Costanzi, depicting the "Triumph of St. Gregory the Great". The interior decorations of the plasters is by Ferrari (1725); a "Madonna with Saints Andrew and Gregory", by Antonio Balestra (1734), on the high altar. The second altar on the left is topped by the "Madonna Enthroned with Saints and Blessed", a famous work by Pompeo Batoni (1739). Down the left nave is the Salviati's CChapel, designed by Francesco da Volterra and finished by Carlo Maderno in 1600. Next to this hapel there is the Oratory of Pope Gregory I, where it still retains the marble chair on which sat the pontiff.