In the Hun­gar­i­an city of Buda there is one of the most amaz­ing cas­tles in the world — the Roy­al Palace in the Buda Cas­tle. It was built on a high hill by order of King Bela IV of Hun­gary, who ruled in the 13th cen­tu­ry to pro­tect against the Tatar-Mon­­gol yoke. Over time, the cas­tle was sur­round­ed by build­ings and a city appeared, called Buda.