Italy, Campania, Naples, Castel Nuovo, also known as Maschio Angioino.

Italy, Campania, Naples, Castel Nuovo, also known as Maschio Angioino.

Italy, Sicily, Palermo, The Cathedral.

Italy, Sicily, Palermo, The Cathedral.

Uzbekistan, Bukhara, Outer walls of the Ark Fortress, Registan Square.

Uzbekistan, Bukhara, Outer walls of the Ark Fortress, Registan Square.

Uzbekistan, Bukhara, Entrance, outer walls and viewing gallery of the Ark Fortress, Registan Square.

Uzbekistan, Khiva, Kunya Ark, also known as Kohna Ark, housing Museum of Ancient Khorezm, Ichan Kala.

Uzbekistam, Khiva, Akshi Bobo, a tower of Kunya Ark, on left, and outer wall of Ichan Kala.

England, County Durham, Durham, The Keep, Durham Castle.

England, County Durham, Durham, Entrance to Durham Castle.

Egypt, Alexandria, Citadel of Qaitbay, also known as Fort of Qaitbay.