The ancient city of Dystos was founded on the imposing and precipitous rocky crag of Kastri, which towers over the plain near Lake Dystos. The settlement's location in the Euboean hinterland, at a short distance from the shore, encouraged both sea and land communications with the rest of Euboea and the coasts of Attica. A road connected the settlement to the nearby port of Argyros, modern Porto Buffalo. Theopompus's reference to 'Dystos, city of Euboea' in his Philippica, related by the writer Stefanos Byzantios, is the only written reference to the ancient city. The ancient word 'dystos' means 'unhappy', but according to recent theory the name may originate from a submersion or sinking of the area and allude to the related geological phenomenon.
The shores of Lake Dystos have been ideal for the establishment of communities since prehistory. Obsidian blades and pottery sherds from the area date the earliest settlements back to the Neolithic period. An organised settlement was formed on the hill near the lake many centuries later, in the Archaic period or earlier. The town thrived in the Classical and Hellenistic periods, and may have played an important role in the first half of the fourth century BC during an attempt by Philip II of Macedon to control the political situation in Euboea by instigating a rebellion against the oligarchic ruler Plutarch. A strong fortification wall was constructed around Dystos and a smaller enclosure was erected on the hilltop in the fourth century BC.
An edilitary relief of the fourth century BC suggests that the earliest attempts to drain Lake Dystos date back to at least this period. The relief, originally from the temple of Apollo Daphneforos at Eretria, was discovered on Tzamiou Square (formerly Fylakon Square) at Chalkis in 1860 and is now in the Epigraphical Museum at Athens. The outline of two figures, probably Artemis and Leto, is still visible. Below these is a text refering to a contract between Chairephanis, the contractor, and 230 citizens of Eretria for the draining of Lake Ptechon, most likely Lake Dystos. The contract, whose terms are still applicable today, included the installation of sewage pipes, drains, and sumps for directing water into natural subterranean crevices.
The discovery of ninety-four denarii of the Roman Republic (Vyrron Treasure) indicates that the port of Dystos was still used in the Roman period. Little is known on Byzantine, Venetian, and Ottoman Dystos, but the area probably shared the same fate as the rest of central Euboea. It was probably under the juristiction of the episcopate of the Straight or the episcopate of Avlon in the Early Byzantine period, and the remains of churches suggest that it was inhabited throughout the Byzantine period. A fortified enclosure and a tower used for controlling the area and communicating with the neighbouring towers of Karavos and Koutoumoula, or Katomoula, were built on the hill under the Venetians.
The ancient site of Dystos was identified in the early nineteenth century thanks to the small, now abandoned, nearby village, which bore the same name. Its ruins attracted a number of scholars and archaeologists, including Ludwig Ross (1844), A. Rangavis (1853), and H. G. Lolling (1876 -1877). Theodore Wiegand (1895) was the first archaeologist to record its ancient ruins in 1898. Much later, in 1976, German archaeologists Ernst-Ludwig Schwandner and Wolfram Hoepfner and their teams produced a more precise plan and studied the remains of buildings on the hill.