The Monastery of Agios Nikolaos of Karia is located between two heights, in the center of Cynuria, at an altitude of 870m above sea level. According to one version of the origin of the monastery's name, it owes its name to a single walnut tree, standing beside the fresh water spring of the monastery ("Karia" could be an old word for Karydia", the Greek word for "walnut tree"). Another story is that the name comes from the place name of Karia, which is preserved in the ruins of an adjacent area, and is related to the glebe of the monastery.
The monastery is mentioned in Turkish records and documents of 1620-1621, in which the residents reportedly ask for the reparation of their church, more specifically the katholikon of the monastery, which is of the Athonite type of architecture. The structure complex is comprised of three wings, in the shape of the Greek letter "Π" around the central garden. The Monastery contains a small library. It also contains murals, but unfortunately they are mostly destroyed by the humidity of the place. The monastery also houses an icon of Agios Nikolaos (Saint Nikolaos), which dates back to 600 AD, and has become corroded due to its years.
The monastery was appointed as Stauropegic in 1622. The church was painted with icons on its walls in 1638, and in 1734 its floor was decorated with a two-headed eagle (an emblem of the Orthodox Christian church), motifs of plants, and depictions of animals. It was raided by the Turks in 1770, but its residents and monks kept buying land for the monastery until 1784, increasing its realty value as a result. The monastery also played a major role in the Revolution of 1821, and in 1829 it funded the creation of many schools for the newly-formed Greek nation.
It became a monastery for women in 1970, although this became official in 1993. The monastery celebrates Agios Nikolaos every 6th of December and 8th of July. Unfortunately, it is not easily accessible during the winter.