The archaeological site at Kato Samiko, north of Lake Kaiafa, has been tentatively identified as the ancient city that was successively named Macistus, Arene, and, finally, Samia, or Samikon, or Samos. Its strategic location controlled both the fertile plain of Samiko and the road connecting Pisatis with Triphylia and western Messenia. The city had two citadels: the prehistoric acropolis on the rocky crag of Kleidi and the Classical acropolis to its east.


Cyclopean walls protected the prehistoric acropolis, whose remains date from the Middle Helladic and Late Helladic periods. A large cemetery of Middle Helladic tumuli and a tumulus with many graves and a wealth of important grave gifts of the Middle Helladic - Late Helladic III periods were discovered in this area. Late Helladic III pottery was also found on the Classical acropolis, where a guard-tower for the prehistoric settlement at Kleidi was probably located.


The Classical acropolis is located on Elliniko hill, on the west slopes of the Lapitha mountain range. Part of the lower city probably stretched northwest of the acropolis, in the area of Lake Agoulinitsa, which is now drained. Moveable archaeological finds date the site's occupation from the fourth century BC until the Roman period. By Strabo's time, the fourth-century fortification walls, known under the name of 'Samikon', were the city's only standing structure. The site can also be identified as ancient Macistus, which, according to Herodotus, was part of the Dorian Hexapolis founded by the Minyans in Elis Triphylia. Herodotus mentions the Samian Poseidion, a sacred wood dedicated to Poseidon, which archaeologists have looked for on the beach. In Strabo's day, it was the citizens of Macistus who tended the Samian Poseidion.


A Roman bathhouse and an Early Christian church are located north of the Classical acropolis. Medieval remains suggest that Kleidi was fortified during the Middle Ages, probably because of its strategic location.