San Marco Evangelista al Campidoglio, Rome

San Marco is a minor basilica in Rome dedicated to St. Mark the Evangelist located in the small Piazza di San Marco adjoining Piazza Venezia. It was first built in 336 by Pope Mark, whose remains are in an urn located below the main altar. The basilica is the national church of Venice in Rome.
History.
In 336, Pope Mark built a church devoted to one of the Evangelists, his patron saint, St. Mark, in a place called "ad Pallacinas". The church is thus recorded as "Titulus Marci" in the 499 synod of Pope Symmachus. At that time it became one of the stational churches of the city (Monday of the third week in Lent).
After a restoration in 792 by Pope Adrian I, the church was rebuilt by Pope Gregory IV in 833. Besides the addition of a Romanesque bell tower in 1154, the major change in the architecture of the church was ordered by Pope Paul II in 1465–70, when the façade of the church was restyled according to the Renaissance taste with a portico and loggia, using marbles taken from the Colosseum and the Theatre of Marcellus. The façade is attributed to Leon Battista Alberti. 
Paul II being a Venetian by birth, assigned the church to the Venetian people living in Rome.
The last major reworking of the basilica was started in 1654-57 and completed by Cardinal Angelo Maria Quirini in 1735–50. With these restorations, the church received its current Baroque decoration.
Interior.
The floor of the church is below the ground level of the Renaissance period, and therefore steps lead down to the interior. The church retains its ancient basilica format, with a raised sanctuary. The inside of the church is clearly Baroque. However, the basilica shows noteworthy elements of all her earlier history:
In the portico are several early Christian grave stones, as well as the gravestone of Vannozza dei Cattanei, the mistress of Cardinal Rodrigo Borgia.