The actual Cathedral of Monteporzio dates back to 1666 and was completely rebuilt after the demolition of the previous church, which was also dedicated to San Gregorio Magno. The façade has double orders of pilaster strips in sperone stone with Doric and Ionic capitals, interchanging with small brick wall panels and overcome by a triangle pediment containing a large marble emblem.
The previous parish church, built in 1580 by the will of Pope Gregory XIII, had a wide, splendid appearance and for this was graded archpriesthood. In 1616, it was in a complete state of neglect when it was taken over by Cardinal Scipione Borghese. In 1666, Prince Giovan Battista Borghese ordered the church to be demolished and reconstructed. The work was assigned to architect Carlo Rainaldi who engaged excellent artists well known at that time in Rome such as Pietro Jacomo Mola (construction and interior decorations), Francesco and Cosimo Fancelli (sculpture decorations), Giacinto Brandi, Ciro Ferri and Guglielmo Courtois (painters of the altarpieces)
Cardinal Henry Duke of York consecrated the Cathedral on 1st June 1766.