Mělník Chateau, originally named Pšov, is situated above the confluence of the Elbe and the Vltava, above the river and the sloping vineyards. The name is derived from the name of the Slavic tribe of Psyovians and has been preserved in the name of Pšovka Stream and the former village, nowadays urban area of Pšovka.

According to the Chronicle of Bohemians by Cosmas of Prague, the last prince of the Psyovians, Slavibor, married his daughter Ludmila to Bořivoj I, Duke of Bohemia. Legend has it that Princess Ludmila often stayed here and raised her grandson Wenceslaus who cultivated vine at the chateau. St. Wenceslaus is depicted in lunettes by the Czech painter Karel Škréta on the first and second floor of the chateau.