Kremenets (krĕmĭnyĕtsˈ) [key], Pol. Krzemieniec, city, in Ukraine. Founded in the 11th cent., Kremenets was part of the Kievan duchy and in the 13th cent. became a fortified city of Halych-Volhynia. After the Polish-Lithuanian union in 1569, it served as a royal residence. The city passed to Russia during the third partition of Poland in 1795. It was again under Polish rule from 1919 to 1945, when it was seized by the USSR.