The Sinaia Monastery, located in Sinaia, in Prahova County, Romania, was founded by Prince Mihail Cantacuzino in 1695 and named after the great Saint Catherine's Monastery on Mount Sinai in Egypt. As of 2005, it is inhabited by 13 Christian Orthodox monks led by hegumen Macarie Bogus. It is part of the Bucharest archdiocese.
Situated in the Prahova Valley, the monastery gave its name to the nearby town of Sinaia. The monastery consists of two courtyards surrounded by low buildings. In the centre of each courtyard there is a small church built in the Byzantine style. One of them—"Biserica Veche" (The Old Church)—dates from 1695, while the more recent "Biserica Mare" (The Great Church) was built in 1846.
The monks possess a library that is a repository for valuable jewels belonging to the Cantacuzino family, as well as the earliest Romanian translation of the Bible, dated 1668.
Take Ionescu, former Prime Minister of Romania, is buried on the grounds.
Prince (Spătarul) Mihail Cantacuzino founded the monastery upon his return from a pilgrimage to Mount Sinai. The first buildings were completed between 1690 and 1695. It was designed to serve as a monastery as well as a fortified stronghold on the route from Brasov to Bucharest.
The initial plan was for the monastery to hold 12 monks, to imitate the Twelve Apostles, but in time the number of monks grew.
In the midst of the Russo–Turkish War, 1735–1739, before deserting the monastery, monks hid the valuables by burying them inside a bell. During a battle, the Turks defeated troops stationed within the walls of the monastery. The Ottomans burned the area and broke through the wall in two places.