The Cattolica was built in the 9th century, when Calabria was part of the Byzantine Empire. The name derives from the Greek word katholiki, which referred to the churches provided with a baptistery. It is one of the most important examples of Byzantine architecture, together with the church of San Marco in Rossano Calabro.
The Cattolica follow a plan with 'inscribed cross', typical of the middle Byzantine age. The interior is divided by four columns into five similar spaces. The square central space and the angled ones are covered by domes. The angled ones have tambours with the same diameter, while the central dome is slightly taller and larger.
The western sides lies on free rocks, while the southern area, ending with three apses, stands on three stone bases. The construction is in bricks.
The interior was once entirely covered with frescoes. The left apse has a bell built in 1577, when the church was converted to the Latin rite. The interior has also several inscriptions in Arabic, which have led scholars to suspect it could have been also used as a Muslim oratory.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.