Castel del Monte, 60 km from Bari, is one of the 54 Italian sites that UNESCO included in its World Heritage List in 1996. Built by Frederick II of Swabia in the 13th century, the castle dominates the surrounding landscape with its massive octagonal structure. The work is universally considered a brilliant example of medieval architecture, but in reality it combines different stylistic elements, from the Romanesque style of the lions at the entrance to the Gothic frame of the towers, from the classical art of the internal friezes to the defensive structure of the architecture and the delicate Islamic refinements of its mosaics. The mathematical and astronomical rigor of its plan, based on the number eight as a guide number and its positioning, designed to create particular symmetries of light on the days of the solstice and equinox, create a symbolism that has fascinated scholars for centuries, leaving visitors with a feeling of pleasant enigma.