1. Thisvi in the course of time

The habitation of Thisvi, as attested by archaeological data, was continuous from the Mycenaean until the Christian times.

According to the mythological tradition, it owes its name to the nymph Thisvi, daughter of the river-God Asopos. The catalogue of ships in the Iliad lists Thisvi among the cities that took part in the Trojan War; there Homer calls Thisvi «πολυτρήρωνά», because of the large number of pigeons that lived in the area of its seaport. At the end of the Archaic period it was an autonomous city and member of the Boeotian League (around 525-520 B.C.). Thisvi participated in the Third Macedonian War (172-168 B.C.), supporting king Perseus of Macedonia, however, a little after the war’s breaking, it was besieged and finally taken by the Romans.

In the 2nd c. A.D., Pausanias, while describing Thisvi, offers infomation on the existence of a sanctuary of Hercules there and the celebration of a feast honoring him. He makes a special mention on the presence of an ancient embankment which functioned as drainage work. In that way, the valley south of Thisvi did not stagnate, but, on the contrary, it was exploited as arable land.

In Thisvi survive the remains of two fortified citadels. The older one is located on the hill north of the modern village, where the site of ancient Thisvi lies. It is the Palaiokastro or Upper Citadel, on whose walls at least four building phases are discernible, from the archaic until the late Roman-early Christian times. However, it still remained in use later on, during the middle and late Byzantine period.

The Lower Citadel, which is also called Neokastro, is dated to the Hellenistic period, with Byzantine era-additions. Its architectural remains are traced in the south side of the site.

Outside the walls, on the rocky hills, a large number of tombs have been cut. Their dimensions vary according to the arcosolia formed in their interior, while isolated arcosolia are present, too. They go back to the early Christian period, yet, it is not impossible to belong to an earlier period – at least some of them – in use until the early Christian times.

A large number of inscriptions from Thisvi has been collected, dating from the 5th c. B.C. until the Roman times, and mosaic floors have been located, most probably belonging to early Christian buildings. A large number of ruined churches, covering the entire Christian era, prove its inhabitants’ way of living under favorable socio-economic conditions for that given period.

2. Thisvi/Kastorion

Written sources regarding Byzantine Thisvi are insufficient and do not bear evidence of its special characteristics nor of the way its society was organized. Its ancient name was in use until the early Christian times, only to be abandoned later. At the end of the late Byzantine and during the Ottoman period, it reappears under the name “Kakosi”, until 1915, when the settlement was renamed Thisvi again. However, the continuous habitation of the area during the middle and late Byzantine period is attested through the archaeological research, mainly field surveys, conducted at Thisvi from the mid-19th c. The continuous research and the correlation of the sources anew led to the link of Thisvi with the place name “Kastorion”, mentioned in the 10th-century Life of Hosios Loukas. Identifying Byzantine Thisvi with Kastorion is due mostly to a tax cadastre of 1466/7 for the sancak of Euboia. It employs a second name for the village Kakosi, also called “Kastoria”. Byzantine Thisvi / Kastorion could also be identified with a 12th-century bishopric seat, held by «ο Καστορίου» or «Καϊστορίου», subordinate to the province of Thebes, and with an early-13th-century one, mentioned in a papal epistle as bishop Castoriensis.

Kastorion is believed today to be the indisputable birthplace of Hosios Loukas, founder of the homonymous monastery in Boeotia. His Vita, whish describes his parents' escape from Aegina for fear of the pirates in the mid-9th century, reports that they sailed to the harbor of Vathy, as the bay south of Thisvi is still called today, the seaport of the ancient town. The nearby mountain, Saint John or Agiannis, is identified too with the place where Hosios Loukas led his ascetic life and which was called in his Life Ioannitzi or Iannitzi.
Until recently Delphi was recorded as his birthplace, because its pre-revolutionary name was Kastri and was thought as identical to Kastorio from the Life of Hosios Loukas, since actually Delphi were not far from the monastery he founded.

In the area inside the walls as well as outside them there is clear evidence of human activity in the Byzantine period. On the twin citadels of Thisvi there are attested building phases and edifices from the Byzantine era. Among them is included a freestanding tower at Neokastro, built on the ruins of an older one. Its reuse is linked to 12th- and 13th-century sherds scattered in the surrounding area. Floors paved with stones have been unearthed, connected with the habitation of the area in the Byzantine times.

At the end of 9th – mid-10th c. Kastorion was called a large village, yet according to the archaeological evidence, already in the 11th or the 12th c. was one of the most important towns of Boeotia. The connection of the harbors with the Peloponnesian shores and the fact that the access to central Greece was much shorter through Thisvi, contributed to the town’s particular commercial significance. Through Thisvi the travelers between East and West avoided the circumnavigation of Attica and the Peloponnese.

2.1. Commercial and economical significance

Very important for the commercial transactions that took place in the natural harbors of Thisvi was the existence of organized settlements on the coastal islets, such as Kouveli and Makronesos. On Kouveli, lying a few kilometers south of Hagios Ioannis, have been found architectural remains going back to Late Antiquity, as well as a 7th-9th-century settlement, with an organized road and urban system. A church has been located among the ruins.

On the islet called Makronesos the research has located harbor facilities and many settlement remains in a naturally defended site called Diporto. The settlement at Diporto seems to have been of a permanent nature, despite the lack of water, a need perhaps met through the transfer of water from Thisvi by the inhabitants and its storage inside cisterns. On Makronesos four habitation phases have been discerned, from the 5th until the 19th c.

The aforementioned islets are probably linked with the intense commercial activity of the valley of Thisvi, as a transfer center for various goods between the Corinthian Golf and central Greece.

The commercial significance of Thisvi seems to be related to the agricultural and stock-breeding activities of the inhabitants, as well as to the production of genuine purple for dying luxurious clothes. This dye comes from a gland found in the shell of porphyra, large quantities of which were recorded by the Irish politician and diplomat sir Thomas Wyse in 1858 at Thisvi. Even today heaps of shells, belonging to the variety of murex purpurea, are visible on a lot near Neokastro. These are accumulations of wastes after the boiling and the smashing into pieces for the extraction of the precious dye, without yet being ascertained to which chronological period they belong.

Nevertheless, the word ‘kastorio’ means a kind of coloring, the genious purple, coming from a kind of shells. In the 12th c., also, Al Idrisi, a Muslim geographer, mentions a harbor on the Corinthian Golf called ‘of the dyers’. Thus, it is not impossible that the procedure of purple production or some of its phases at Thisvi was continued during the Christian era, even if it had started in much earlier times.

Finally, regarding the agricultural production of the area, apart from the traces of drainage works, some stepped arrangements (stone-bench) have been observed serving in the cultivation of the valley of Thisvi.

3. Churches of Thisvi

The great importance of Thisvi is attested also by the large number of churches in its area, several of which are traced back to the Byzantine period. In their wall-masonry material from ancient buildings is often used.

The most important of them was the ruined church of Saint Luke. It lies to the north of the modern village and has more than two building phases. It is most probably the episcopal church of Kastorion, dedicated to the famous saint (hosios) Loukas of Boeotia. It seems that it was initially built according to the architectural type of the transitory cross-shaped church. Its semicircular apse survives in considerable height and plenty of ancient building spolia lie in the area of the church ruins. To its northwest there is a cistern and to its north side an annex, identified as chapel. In the 19th century a small marble pier with pear–shaped ending from a middle Byzantine altar screen was found, as well six grave stones on its floor.

The ruined church of Hagia Triada belongs to the middle Byzantine period. A large part of its walls were torn down by 19th-century foreign travelers for the sake of seeking ancient inscriptions. An arched entrance was still standing until then. Today the east side of the church survives with its three semi-circular apses.

The ruins of Hagia Triada lie west of the church of Hagia Paraskevi (19th c.). In the latter’s holy sanctuary a massive slab had been used, broken in one of its narrow sides, with an inscribed monogram of cross, while an architectural member, perhaps an impost, was used as a base to support it.

To the southwest of the church of the Dormition of Theotokos, standing in the village square, built over the site of an earlier church, is a small space with an iconostasis in its centre. To the east large square stones have been accumulated and a column shaft is visible. There probably was the site of the Byzantine church of Hagia Kyriaki. To the southwest of this site lies the church of Hagioi Taxiarchai, a Post-Byzantine single-nave church. It has been erected upon the foundations of an earlier one, whose south wall served as precinct.

In the courtyard of the Post-Byzantine church of Prophet Elijah stands plenty of ancient building material, used for the erection of Byzantine churches at Kastorion.

Ruins of two more Byzantine churches are visible northwest of the remains of the church of Saint Luke. The one, dedicated to Saint Vlasios, has three apses, while the second one is of small proportions with a single apse.

The apse of the Savior church, west of Palaiokastro, is quite interesting. Its upper part is two-sided, while from the ground to halfway up it is a semicircle.

The church of Saints Constantine and Helen lies to the south of the village, and it should probably be associated with the rock-cut tombs. It is a single-nave church, with large dressed stones in its corners. On its upper parts brick stones are irregularly applied in the joints. This ruined church ends in a semicircular apse, attached to the rock. Traces of it are discerned on the upper parts of the natural rock. Parts of the floor or floor bedding survive inside the conch. The initial phase seems to go back to the middle Byzantine period.

Building remains identified with churches are reported inside the citadels, while many sculpted members, some of them coming from religious buildings, have been found in the houses of modern Thisvi.