The fortifications of the ancient city of Stymphalos have attracted some attention since the early 19th century, when Edward Dodwell became the first European in modern times to record his visit to the Arkadian valley. Since then the enceinte has come to be known in considerable detail mainly thanks to select excavation by A. Orlandos from 1926 through 1930, and more recently thanks to the surveying and excavation of the site by the University of BC from the years 1982 through 1997.
The majority of the fortification system and of the urban area of the city itself lies on the level terrain to the north of the modern lake. The city is hemmed in by the slopes of the Kylene range to the north, by spurs of the same range to the west, by the low acropolis which projects above the lake bed, and by the lake itself, to the south. Above the valley floor the fortifications traverse the slopes of the low acropolis which dominates the western and southern boundaries of the city. The acropolis is formed by a spur of the Kylene range which runs roughly on an east/ west axis down the centre of the valley. From the large rectangular battery at the summit the walls traverse the north and the south slops of the acropolis before descending onto the valley floor. The circuit survives in varying degrees of preservation and enough of it remains to reconstruct its gently curving outline across the valley floor, and the enclosure which protects the acropolis. Forty five regularly spaced towers, seven gates, and one postern have been identified thus far, although several hundred meters of the wall in the northern area of the city have not yet been located. The total length of the known remains is just over 2 km, and a tentative reconstruction of the total length including the missing stretch in the north approaches 2.5 km (enclosing an area of approximately 30 hectares).
The wall itself was comprised of a superstructure of sun dried brick which stood on top of a stone foundation ranging from 4.00 m to 2.5 m in thickness depending on the location along the circuit. The foundation is composed of two facing walls of limestone blocks of varying masonry styles, which enclose a core of packed earth and rubble. This foundation stands above the ground for approximately one quarter of the length of the circuit, after which it makes the occasional appearance through the turf on the banks of the lake, or in the furrows of farmers' fields. Rectangular and circular towers can be found at different locations around the enceinte and average 6.25 to 6.5 m in diameter (or width). For the most part these towers are spaced at an average of 36/8 m (centre of tower to centre) consistently around the lintel of the wall. Three larger towers survive in fairly good condition and range in size and shape from the 22 x11 m rectangular battery at the summit of the acropolis, to the 6.5 x 8.5 m hexagonal tower on the south wall of the acropolis 20 m above the lake bed.