Medzhibiz Castle is a monument of fortification architecture of the 14th-19th centuries. The name comes from the location near the confluence of the South Bug and Buzhok rivers. Medzhibyzh was first mentioned in the Ipatiev Chronicle in 1146. In the 13th century. Medzhibizh belonged to the Bolokhiv land, but in 1255 Prince Danylo Romanovych annexed it to the Principality of Galicia. Mezhybyzh Fortress was declared an architectural monument in 1963. In 2001, the State Historical and Cultural Reserve "Mezhybyzh" was created. Olesky Castle is a monument of palace and fortification architecture of the 14th–18th centuries. The first written mention of it was recorded in historical sources in 1326. However, the earliest fortifications on the hill, which advantageously dominates the area in the floodplain of the Libertsia River, were built as early as the 13th century, during the time of the disintegration of Kyivan Rus into separate principalities. It is likely that the first stone castle was built by one of the sons of the Galician-Volyn prince Yury Lvovych - Lev or Andriy. Since 1975, a museum has been opened in Oleskyi Castle.