On an islet in the lagoon of Tholi, which constitutes its own separate basin, and near the natural fish farm (an ivari), are preserved remains of the Monastery of Agios Ioannis. It was a subsidiary of the neighbouring monastery of Taxiarches on the coast opposite, with which it was formerly connected by road. The two complexes have many common morphological elements and a fortified style of architecture. This latter demonstrates that, due to their position near the coast, they were in danger of being raided, probably by pirates who had their stronghold on the Echinades Islands, near the mouth of the Acheloos.
Remains of the monastery are preserved on the highest point of the island, including those of the katholikon and a three-storey fortified tower. The church of the katholikon was of the cross-in-square type of church; today it has collapsed. The tower is almost square, measuring 8.84 x 6.10 m, and is preserved to a height of 7 m. Access to the upper level would have been by a movable wooden staircase. It is a typical example of a monastic tower-house, designed for protection against raids. It is reinforced with timber trusses and has three battlements and eleven rifle slits.
From what little information is known about the monastery, it can be deduced that it was from the 18th century and that by the beginning of the 19th century it had been destroyed, probably during the Orlofika debacle.
