Ostroh is an ancient town, the history of which began in the times of Kyiv Rus. It was first mentioned in 1100 in the Hypatian Codex. In the 14th century, the city became a residence of Princes Ostrozkiy, the descendants of Rurik. On the site of Old Rus settlement the Ostrozkiy constructed the castle, which became their family estate. They fortified not only the castle, but the whole town as well. Fragments of the fortifications have been preserved. In the 1980s, the old Ostroh sites were recognized as the state historical and cultural reserve.
Of all buildings of Ostroh Castle, the following have survived: Guard (Murovana) Tower, the New (Round) Tower, the Bogoyavlenskiy (Epiphany) Cathedral and the belltower. The oldest monument is Guard Tower, its construction dates back to the 14lh century. The tower served as the donjon of the castle – the internal citadel to protect citizens even when the enemy penetrated into the city. With thick walls fortified by stout buttresses and narrow loopholes, even now the tower has an impressive and convincingly reliable look. Nowadays it houses Ostroh History Museum and Art Museum. The picturesgue Round Tower decorated in Renaissance style is crowned by castellations.
Of the town’s old fortifications, Lutsk and Tatar gate towers of the 16lh century have survived. Nowadays Lutsk Tower houses the museum of book and printing, famous for its rich collection of rare old printed books.