The Castle of Princes Ostrozkyi is the residence of princes Ostrozkyi, built on an arched land at the merge of the rivers Sluch and Ikopot, and it is an organic part of Starokonstiantyniv urban infrastructure in the last quarter of the 16th century. The uniqueness of the castle in Starokonstiantyniv is, first of all, that it was established and built together with the whole city in a rather short time. The formal reason for the construction of Konstiantyniv city and the castle was the gap that existed in the defense system of Volyn lands on the path of Tatar invasions.