If heaven really does exist, let's hope it looks a little bit like the inside of Seville's Alcázar. Built primarily in the 1300s during the so-called 'dark ages' in Europe, the castle's intricate architecture marks one of history's architectural high points. A fusion of Islamic and Christian artistry — Mudéjar tilework, horseshoe arches, sunken gardens with orange trees. Used as a filming location for Game of Thrones.