Prague Castle (Czech: Pražský hrad) is a castle complex in Prague, Czech Republic, dating from the 9th century and the official residence of the President of the Czech Republic. The castle was a seat of power for kings of Bohemia, Holy Roman emperors, and presidents of Czechoslovakia. The Bohemian Crown Jewels are kept within a hidden room inside it. The Guinness Book of Records lists Prague Castle as the largest ancient castle in the world. It occupies an area of almost 70,000 m2, at about 570 meters in length and an average of about 130 meters wide.