Theisoa is built at an altitude of 500m in the south of the prefecture of Elis and close to the ancient city with the same name. It has approximately 90 residents and it is located on the eastern slopes of Mount Minthi near the Mount Lykaio. Its old residents are considered as the most ancient descents of Parassios family, known for their simplicity, goodness and politeness.
On the top of the adjacent hill you will find the medieval castle of Agia Eleni (St. Eleni), a Frankish fort of the 13th century. In 1966, during the road construction, a cemetery was discovered, dated from the Hellenistic period (3rd to 1st centuries BC). The actual village was founded during the byzantine period, between 1057-1135, under the Comnenian dynasty. During the Turkish rule, the village was named Lavda. It was in Theisoa where the battle of Agios Athanasios took place in 1821, in the years of the Greek Revolution, in which Kolokotronis also participated. In 2007, the village came close to destruction by a big forest fire.