Wawel Castle is a castle residency located on a hill by the Vistula River in central Kraków. Built at the behest of King Casimir III the Great, it consists of a number of structures including Wawel Cathedral situated around the Italian-styled main courtyard. The castle, being one of the largest in Poland, represents nearly all-European architectural styles of medieval, renaissance and baroque periods. The Wawel Royal Castle and the Wawel Hill constitute the most historically and culturally significant site in the country. In 1978 it was declared a UNESCO World Heritage Site as part of the Historic Centre of Kraków.