Situated on western Murge hill, it was listed as Italian National Monuments in 1936 and in UNESCO World Heritage, in 1996. In 2014 it was the thirtieth most visited Italian site. Its origin is placed officially on January 29, 1240, when Frederick II Hohenstaufen ordered Riccardo da Montefusco the construction of a Castle at previous church of Sancta Maria de Monte. During seventeenth century followed a long period of neglect, in which Castle was stripped of furniture and marble wall decorations, and became not only prison but also shelter for shepherds, bandits and political refugees. The building is octagonal, and in each corner engages octagonal turret too. Interior space is divided into two floors and trapezoidal rooms. Central square is covered by vault, the lateral ones by two cloves of barrel vault for each room. Communication between the lower and upper levels is by spiral staircase (not present in all towers) in a counterclockwise direction. The upper floor is more refined, enlightened by the presence of mullioned dubble windows and, on the side facing towards Andria, a mullioned window. In the courtyard there is a feeling that the first floor serves as socket on the top floor. The decoration of the building, in a very rich source, is notable for keystones decorated with mythological creatures and plant motifs (typical of Swabian realism). Construction materials are three, employees not random: limestone, white marble and coral rubble. Although it is commonly called "castle", the true function of this building is unknown, being devoid of military elements and place in a non-strategic location. Rather, strong symbolism seem to indicate that the structure was more a kind of initiatory temple, synthesis of sophisticated mathematics, geometry and astronomy. The choice of octagon shape, for example, result from Dome of Rock in Jerusalem. Entire building is imbued with strong astrological symbols and its position is designed so that on solstices and equinoxes shadows cast by the walls have a particular direction. On May 2, 1977 it was issued a stamp that shows a perspective view; in 1998 Castel del Monte was impressed on Italian 1 cent of Euro.