Castel del Monte is located on a small hill near Adria, in the province of Bari (Apulia, Italy). It was built in the 13th century, during the reign of the Holy Roman Emperor Frederick II. Originally used as a hunting lodge, it was later turned into a prison, used as a refuge during a plague, and finally fell into disrepair. From 1996 it is protected under the UNESCO heritage law. Horizontal color image.