San Marco is a minor basilica in Rome dedicated to St. Mark the Evangelist. 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.
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.
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:
the apse mosaics, dating to Pope Gregory IV (827-844), show the Pope, with the squared halo of a living person, offering a model of the church to Christ, in the presence of Mark the Evangelist, Pope Saint Mark and other saints. The wooden ceiling, with the emblem of Pope Paul II (1464-1471), is one of only two original 15th-century wooden ceilings in Rome, together with the one at Santa Maria Maggiore.
In the portico are several early Christian grave stones, as well as the gravestone of Vannozza dei Cattanei, the mistress of Cardinal Rodrigo Borgia.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.