The village of Olympoi was founded at the 13th century, at the Palaiologoi historical period. It is one of the medieval villages that were not destroyed at the earthquake in 1881. Olympoi, as Mesta and Pyrgi, it was created by conjunction  of a lot small villages (Ano Olympoi, Vrakana, Theia, Kastraki, Alona- Zavaza, Gonies-Salagona, Vrekos), for protection from  pirates. That means that the residents of the villages and settlements abandoned their houses and went to live in Kato Olympoi in order to be safe from the pirate raids.
The settlement of Kato Olympoi used as its main church the small church of Agias Theodosias. Later, as the union of villages took place, Agia Paraskevi Church was build. It is said that in this church was placed the chancel screen of Agios Ioannis church that was located on the village Ano Olympoi, which the residents of the village had taken with them when they left from it.
The village was encircled by castle walls, having an oblong square shape. The castle had four crenellations. Two of those were located at the corner and were bigger than the others. The alcazar height was 7 metres and the height of crenellations, 5 metres.
The residents’ entrance and exit was possible from only one door, which is saved till today in the place called Kato Porta. Afterwards 1821 were also constructed two new doors, one in Agios Georgios and the other in the school. The central door had to be closed at night, for the pirates fear. In case of a pirate raid, all the residents entered into village, in order to defend themselves.
The warning of pirate ships appearance was given by men that were kept a lookout in observation towers. They lived in observation towers, at coastal locations and watched the region for pirates (An observation tower is saved in Agia Dynami location.). Every time the pirates appeared on the horizon, the watchmen set fire to inform the village residents so they had enough time to take cover in the castle. If the pirates found residents in the countryside, they captured them as slaves and afterwards they assaulted the village. If the pirates achieved to enter into the village castle, then its residents would seek coverage to the second tower which was the tallest and was defended until the end. The second tower is saved till today and is located in the centre of village; it has an area of 245 square meters. It has been re-built by E.O.T.
The current village until 1821 was pruned in the castle area. Later on, that the danger of pirates was eliminated; the residents began to build outside from the castle, too.