Aya Trias Basilica was built in the early 6th century and destroyed during the Arab raids of the 7th century. It was then abandoned, and a small church and other buildings were built to the south. These buildings in turn were abandoned and destroyed around the 9th century. All memory of the basilica disappeared, until it was rediscovered by chance in 1957, when it was partially excavated.
What can be seen of the basilica today is an entrance atrium at the western end of the basilica, (the end furthest away from today's entrance gate). This leads to an entrance lobby, or narthex, spanning the width of the basilica. This in turn leads to a three-aisled nave, with a number of columns still standing. here you can see the remains of a chancel. There is a large central apse and two smaller apses to the north and south. To the southeast of the basilica, you can see the remains of a large cross shaped baptismal chamber, the largest known on the island. It is thought that the other structures you can see here are the remains of the Bishop's Palace.
The narthex and nave are extensively covered with mosaics, mostly geometric patterns. In the northern nave, however, there are some exceptions. In particular, a pomegranate tree, alongside a pair of sandals.
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.