Kallipolis or Kallion is situated on a particularly privileged strategic position, on the western bank of the river Mornos (Dafnos in antiquity), controlling the only road leading from Thessaly and the valley of Spercheios to the interior of Aetolia and to Naupaktos. A crucial moment in the city's history was its destruction by the Galatians in 279 B.C.; almost five centuries later Pausanias described their atrocities in bleak colours. The inhabitants of Kallion who survived rebuilt their city and played an important role in the Aetolian League at the end of the same century as well as in the first half of the 2nd century B.C.  

The archaeological investigations in Kallion were carried out in the 1970s in order to document the city in the prospect of constructing an artificial lake at the dam of the river Mornos. The top plan of the fortification wall was reconstructed, whereas part of the dense settlement between the two main gates, namely the south and the east one, was thoroughly investigated. There were revealed parts of Hellenistic houses, destroyed probably after the battle of Pydna in 168 B.C. In one of the houses were discovered approximately 600 clay seals, namely small pieces of clay which the sender of a letter would stick on the ends of the ribbon which held it tied. Each piece of clay bore the imprint of the sender's seal as a token of authenticity of the author. The seals, which were probably not fired, were preserved due to the fire which destroyed the house. Among the imprints one discerns symbols of city-states, such as Chios, Lamia, Delphi, mythological creatures and profiles of male figures, identified with prominent kings, such as Ptolemy Philopator, Attalus I, Prusias of Bithynia etc. The entire group of seals leads to the conclusion that Kallion or -at least the receiver of the documents bearing them- maintained close ties with the political authorities of large part of mainland Greece, of the islands as well as of the Hellenistic kingdoms. 

Two temple buildings have also been investigated in Kallipolis: a long temple with wooden columns on stone bases, which had succeeded two earlier temples of the 8th and 6th century B.C., was discovered at a distance of about 100 meters south of the wall. A second, smaller temple consisting of a single room, dedicated to Demeter and Persephone, was discovered very close to the south gate of the wall. Inside this temple were found two cult statues, of which that of Persephone was intact, whereas the seated figure of Demeter was fragmentary; along with the statues were discovered their pedestals as well. 

On top of the ruins of the ancient city richly adorned houses were built in the Roman Imperial period (1st-4th century A.D.) along with a small bath complex (balneum); these buildings were destroyed and abandoned in the 5th century A.D. In the medieval period over the ruins of the ancient acropolis was built the so-called Castle of Velouhovo.