The area's natural geography helped to fortify the complex; the southern and eastern sides of the fortress raised upon a 20 metres (66 ft) high cliff, and the northern and western sides separate the city by series of moats that replaced the big ravine.

[citation needed] From 1386, the town of Ostroh belonged to the Ostrogski family, who built the castle.

[citation needed] Both towers were built in the second half of the fifteenth and early sixteenth centuries from sandstone.

The Tatar Tower is worse preserved, with a significant portion of the elliptical part of the building lost.

A building used to stand in the same location, in which the "Azbuka" (alphabet) and the Ostrog Bible were printed by Ivan Fedorov.