The historical Monastery of the Presentation of the Virgin Mary at Petra is found on the northwest side of Olympus, at the starts of the straights of the same name. This old monastery retains only its katholicon, built in 1754 and repaired in 1815. Inside the church walls, sculptures and architectural parts from older, early Christian and Byzantine monuments from the area have been immured. During the 20th century, the monastery operated as a sanatorium (1929-1969) and then as a psychiatric hospital (1970-2004). West of the monastery, near the only stone drinking fountain on the national route towards Elassona, is the site of the Byzantine town of Petra, which had an important castle. The archaeological service discovered the remains of houses and a church from the 14th-15th century Byzantine town at the site known as “Karakoli”. Petra was the seat of a bishopric, known since the 10th century. It was subject to the Metropolis of Thessaloniki, and in its final years before its abolition, in 1896, had its seat in Livadi, Olympus.