The West Archaeological area in Kos Town is located in the centre of the city. This part of the town had been abandoned during the medieval period but was very well excavated and brought to light the most important structures of Ancient Kos.
The Thermae of the harbour
The Thermae (Baths) of the harbour are situated NE of Irodotou Street, and were constructed after the 3rd century AD. They consist of a round chamber with stoas, the walls of which are lined with perforated bricks for heating. Mosaic floors were discovered next to the Thermae, depicting a Medusa with pointed hair, a fish and a thyrsus.
The Northern Thermae
The Northern Thermae (Baths), located NE of 31 Martiou street, date from the 3rd century AD. A large building with a long room with arches and remains of vaults can be seen, as well as hot air-spaces below the baths, while remnants of a travestine structure from the 4th-3rd century BC have been incorporated into the Roman walls. It is likely that these Thermae were built next to a Gymnasium of the Hellenistic Age, but its location has not been yet established.
The Ancient Stadium
The ancient Stadium is one of the splendid public buildings that occupied extensive areas in the western section of the ancient city. Located SW of the ruins of the Northern Thermae in front of the chapel of Agia Anna, the ancient Stadium was the reference point for other monumental athletic buildings situated around it, as is the case with the West and the North Gymnasium. The Stadium dates from the first half of the 2nd century BC, although its construction started during the first building period (4th-3rd century BC).
The Stadium was a rectangular building with a length of 180 m. and a track width of 30 m. It was built on on a small incline on the western hillside of Seraglio, taking advantage of the slope to construct the seats for the spectators in the 4th century BC. In the Roman period, a large tribune with rows of seats (travertine) was added to the west side of the Stadium.
The starting line (aphesis), situated at the north end of the track, was equipped with a mechanism (hysplex) that ensured the simultaneous start of all runners. The aphesis, namely the remains of seven pillar-supports, was discovered in 1900 by the archaeologist Herzog, next to the chapel of Saint Anna. The travertine seats were discovered later by archaeologist Laurenzi, followed by mosaics of Orpheus, figures within octagons and a hunting and fishing mosaic.
West Archaeological site
Exquisite public buildings are situated in the western section of the West Archeological site: the Hellenistic West Gymnasium, The Roman West Thermae (Baths), the so-called Nympaeum, the Floricae of the Thermae (public lavatories) and the Proto-Byzantine Episcopal complex of Kos. At the north end of the site, a large mosaic floor of the Roman period depicts the myth of the Judgment of Paris. Two main streets of the Roman period, decumanus maximus (east-West oriented road) and cardo (North-South oriented road) intersect in the southern section of the site. The area north of the decumanus is occupied by Roman residences, richly decorated with murals and mosaics, as is the case with the House of the Abduction of Europa and the House of Sitinos, which were named after the decorative themes of their mosaic floors.
the Western Gymnasium is the biggest of the three found in Kos and was 180m in length and 90m in width. The Xyston (covered stoa) or the Xystos Dromos, an all-around collonade used for gymnastics during wintertime, was built during the first half of the 2nd century BC. 17 pillars (of perhaps a total of 81), which belonged to the Eastern side of the Gymnasium, made from the island’s white marble, were restored in alignment in the direction NE to SW. The Gymnasium also had an open inner courtyard surrounded by columns.
In Roman Times (3rd century AD), the xyston was repaired, while a Thermae (bath) building and a pool were added to the southern side. The xyston eventually collapsed in 469 AD and its ruins were used as building material for walls of the early Christian period.
The Western Thermae
The Western Thermae (Baths) were built in the 3rd century AD and are located between the stoa of the Gymnasium and the slated street to the East. It was a trapezoid-shaped building, 92m in length and with a width that varied from 33 to 35m. Part of the vaulted room still exists today. The Thermae must have been destroyed by the earthquake of 469 AD and part of it was converted to an early Christian basilica.
To the North of the Thermae, the softstone foundations of a 4th-3rd century BC structure, rebuilt as a residence during the Roman period, are distinguishable. On the North end, one of the largest (14.20X6.65 m) mosaic floors of Kos was found. The mosaic, from the 2nd century AD, is divided into three squares and depicts animal fights. The walls of a private building from the 4th-3rd century BC, converted into a Roman residence, were also found South of the Thermae.
The slated street (Cardo)
The slated street (Cardo), most probably from the Hellenistic Age and repaired during the Roman period, was uncovered at about 160m in length in a NE-SW direction. The ground, made of large travertine slates has been preserved almost wholly for approximately 120m. The carriageway still shows the deep cuts from the vehicle wheels of that time. The sidewalks are 1m wide westward and 2m wide eastward. There is a broad sewer under the carriageway, covered by large porous stone slabs with vaults. Along the cardo there were shops (tabernae), one after the other, from the advanced imperial period.
The stoa of porous stone dating from the 4th-3rd century BC was located east of the slated street. It was rebuilt during the Roman period when other walls were added.
The Forica of the Thermae (Baths) or Nymphaion
The Forica (public latrine) of the Thermae (Baths) or the Nymphaion is a building that lies East of the Cardo and is connected to the Thermae across. It belongs most probably to the 3rd century AD and was destroyed by the 469AD earthquake.
Its ground plan is nearly square (18x20m) and its entrance was located on the Western side. An inner courtyard 7m long, with a well in its center, is surrounded by pillars of white marble and a wall 4.10m high to the West, where three large niches with pools open up. The floor alternates squares of marble and mosaic of geometric forms except two squares depicting dolphins. The pedestal bears traces of columns, 11 of which have been restored. The walls above the columns form double rows of brick-arches, whilst the inner marble walls are 1.85m high.
A wide, deep sewer runs along the Northern wall. Pieces of porous stone supporting the marble slabs were placed on the sewer at regular intervals and constituted the defecation seats on the three sides of the building.
Street with stoas
The street with the stoas or Decumanus has been excavated to about 150m in an E-W direction and meets with the other slated street (cardo) in the SW. This street is the broadest of those discovered in Kos, with its width reaching 10.50m, of which 4.45m constituted the carriage-road. The sewer is skillfully laid under the southern sidewalk The Decumanus of Kos was one of the arched streets that were built during the imperial period in the cities of Asia Minor and East Africa, although its architecture belongs to the first decades of the 3rd century AD.
Blocks of houses
The building blocks, located to the North of the stoa street (decumanus) and to the South of the Acropolis, are separated by two streets, namely a 4m wide street coming down from the high ground and a 6m wide street in a NE to SW direction. One house, rebuilt from an older Hellenistic house, is renowned for its mosaic depicting Europa that adorns the floor of one of its rooms, whilst many diverse paintings decorate a large part of the house’s rooms. A number of important statues, that were unearthed, are now exhibited in the Museum of Kos. In the other two building blocks, East of the stoa street (Decumanus), a house was found with mosaics representing a boar hunt, a bearded Seilinos (water demon) and a duel between Zephyros (god of the West wind) and Ylas (a follower of Heracles).
Sources: Archaeologist Grigoriadou and V. Hatzivasileiou’s History of the island of Kos