The Palaiokastro hill rises in a strategic position overlooking Sergoula beach and the modern settlement of Glypha. The hilltop is crowned by the remains of an important, strong fortification dating in the late 4th – early 3rd ct. BC and protecting some unknown town of the ancient West Lokris. This imposing fortification, built of local grey stone, consists of two precincts. At some points, where the inaccessible rock-cliffs offer natural defense, no wall was necessary. The outer precinct encloses an area 170m by 300m and its masonry is generally impressive, although in some places it seems rather crude and makeshift. Mostly on its north side the foundations of large rectangular towers are preserved. Structural remains on natural terraces between the two precincts probably belong to public or religious installations.
The inner fortification-precinct, of polygonal ground-plan, encloses an area of 100m by 55m. Its pseudo-isodomic trapezoidal masonry, in places with polygonal stones, is very well preserved and a masterpiece in terms of technique/technical execution. Of the eight semicircular towers reinforcing the circuit two, on the east side, protected the gate (1.75m high and 0.80m wide), which was the main entrance to the citadel. Among the remains of various structures within the citadel we point out a built cistern measuring 7.58m by 2.97m.
Outside the fortification, on the hillside that overlooks the modern village of Glypha, large retaining walls of polygonal stones form terraces formerly occupied by the ancient settlement. Excavations at one of these terraces, at the NE foot of the hill, yielded domestic remains of the Hellenistic period. The ancient necropolis was located on the stretch of land where the Palaiokastro hill lowers to meet the modern Naupaktos-Itea road. Remains of graves are visible in this area. According to an inscription found in Glypha a while ago, the goddess Basileia was worshipped here. Basilieia was particularly popular in this region, since her cult is epigraphically attested in other towns of West Lokris, too, such as Tolofon and Physkos (modern Malandrino).