Karakalou is built on a slope on the northeast side of Mt. Athos, half an hour's walk from the sea. Its existence is mentioned as early as the 11th century. The Catholicon is of the 16th century, frescoed in 1716. its feast day is on June 29, honoring the Apostles Peter and Paul. The impressive tower of the monastery as well as the arsenal are also 16th century structures, built with the financial aid of the ruler of Wallachia Peter. Due to lack of space in this monastery there is no Phiale at the courtyard. The arsenal tower is probably older. The library contains 270 manuscripts and approximately 2.500 printed works. The monastery is 11th in the hierarchy of Mt. Athos.