The excavations that took place in the town of Kos from 1935 to 1943, unearthed an entire early Christian layer, within the archaeological zones, dating from the period between the two major earthquakes that struck Kos in 469 and 554 AD. The early Christian Kos Town Basilicas thus uncovered, constituted the most important findings from that period.
The harbour Basilica
The harbour basilica dates from the 5th-6th century AD and was possibly one of the first Christian buildings erected on Kos. Christianity established itself in Kos in the 4th century AD, as attested by the participation of Bishop Meliphron of Kos in sessions of the First Ecumenical Council, held at Nicaea in Bithynia in 325 AD.
72 meters long and 23.50 meters wide, it is considered one of the largest basilicas in the Mediterranean.
The basilica, of which the foundations are preserved, was found and excavated in 1936 by the Italian archaeologist Morricone, at the north end of the Eastern archaeological area, south of the Lozia Mosque and over the ruins of the ancient stoa (item 5). It was built upon the remains of the harbour stoa and the east jetty, which were filled in to create a manmade embankment, so that the church would dominate the area. The basilica was built using spolia from ancient monuments.
The basilica is of the three-aisled, timber-roofed type with atrium and baptistery (item 4). The church proper (naos) had mosaic floors, vestiges of which were found in the narthex, and was divided into three aisles by granite columns with smooth shaft, which the Knights later incorporated in a gateway (doorposts) of the castle of Neratzia. The middle aisle, which was wider, ended in a semicircular apse at the east end. The paved atrium is surrounded on three sides by porticoes. The west portico was double and a stairway on its east side led into the tripartite narthex.
The monument is preserved to the height of the foundations. It seems that during the Hospitaller period, there was extensive removal of building material, in order to erect the castle of Neratzia and the walled burg of the Knights. Stones were taken from the foundations and the east jetty was dismantled, resulting in the opening of a transverse passage that cuts the naos (church) into two. Other materials from the ruins were used to build the Lozia Mosque, which, according to tradition, was formerly the Saint George Church. Fore this reason, some claim that the basilica was dedicated to Saint George.
The baptistry to the south has a cross-shaped basin in the middle and is a miniature of the one encountered at the Baptistry of Agios Ioannis Prodromos at the south of Kos Town.
You can also check the relevant post concerning the Eastern archaeological area.
Another early Christian tripartite basilica, with a narthex and three aisles, was discovered to the East of the Eastern archaeological area. It faces, however, toward the west, and not the east which is the usual direction of churches.