Almost 2km west of the pleasant harbour of Mastichari (with seasonal ferry to Kalymnos), 4km north of Antimachia, are the remains of the 5th century basilica of Aghios Ioannis (reached in 20 minutes by a shore line promenade and path west from the harbour along the coast). The glory of these finds was the extensive and or nate floor–mosaics, most of which have now been covered with gravel for protection: some are still visible, however, in the adjoining rooms to the south of the main basilica. The designs are mostly complex abstract decorations in four principal colours, with occasional insets of birds: in the north aisle are a series of larger animals. The three-aisled basilica itself appears to have been wide (c. 15m) in relation to its length (22m): stairs at the west, show that it had a gallery for women. The impression of width was increased externally by the addition of three rooms constituting a parecclesion or rooms for the clergy on the south side, and a baptistery and ante-room on the north side. The baptismal font, lined with polychrome marbles (including some alabaster), is still visible at the centre of the baptistery—an unusual architectural space, once domed overhead, with mosaic floor below, and its four corners moulded into recessed niches. This highly articulated and decorated space was preceded by a sober, rectangular ‘waiting-room’, with terracotta-tile floor: it has benches around its walls on which the catechumens waited for their call to spiritual re-birth. The apse of the main basilica had the synthronon steps typical of this period; the masonry table of the prothesis, where the elements of the Eucharist are prepared, is visible to its south. The church would have been at the centre of a commensurately large community: excavations in the area have revealed some of its remains, beneath the encroaching modern constructions.
Kos Island is part of the Dodecanese Island group