Take a tour of Castel del Monte in Italy – part of the World’s Greatest Attractions series by GeoBeats. South Italy's Castel del Monte is a stunning monument of medieval architecture. It was completed in 1240 under the Holy Roman Emperor Frederick the second. First used as a hunting lodge, Castel del Monte later became a prison. It also found use as a sanctuary during the time of the plague. The Italian government bought the fortress in 1876. Its octagonal structure was inspired by religious architecture. The iconic palace is very recognizable - it's even featured on the Italian Euro cent coin.