Incorporated into Palazzo Venezia, the Basilica di San Marco was founded by Pope San Marco in honor of Evangelista, who beared the same place, in 336. In 792 it was restored by Pope Adriano I and almost completely rebuilt by Pope Gregorio IV in 833, who ordered the decoration of the apse and the construction of the triumphal arch with mosaics that one still treasures nowadays. 

Cardinal Pietro Barbo, later Pope Paolo II, rebuilt it in most of its actual shapes and made it the Church of Venetians in Rome (1460 circa). Between 1740 and 1750 it was restored by Filippo Barigioni, who modified the interior’s physiognomy with Baroque decorations. 

The façade, consisting of a porch with three arcades with semi-columns leaning on pilasters, defined of the Benedizione, is among the most elegant Renaissance architectural examples in Rome and is a work by Giuliano da Magliano or by Leon Battista Alberti. 

Behind it one finds the little Romanesque bell-tower with three-mullioned windows, adorned by antique green disks. During the restoration works of the the church underground ruins of the first basilica from C. IV were retrieved. 

In the basilica one has also retrieved the bones of many martyrs such as San Marco’s, now treasured under the high altar.