Haut-Koenigsbourg Castle, view of the exterior wall and keep overlooking the Alsace plain, from the grand bastion, Haut Rhin, Alsace, France, Europe

Haut-Koenigsbourg Castle, view of the exterior wall and keep overlooking the Alsace plain, from the grand bastion, Haut Rhin, Alsace, France, Europe

Sultan Qaboos Grand Mosque, Muscat, Sultanate of Oman, Arabia, Middle East

Donaubuehne stage, Klenzepark, Reduit Tilly fortress, Ingolstadt, Bavaria, Germany, Europe

View from Valletta of the fortress Fort St. Angelo in the centre of the Grand Harbour, Vittoriosa, Malta, Europe

Palace of the Grand Master of the Knights of Rhodes, castle of the knights of St. John, historic centre of Rhodes, Greece, Europe

Palace of the Grand Master of the Knights of Rhodes, historic town centre of the city of Rhodes, Rhodes, Greece, Europe

Palace of the Grand Master of the Knights of Rhodes, castle of the knights of St. John, historic centre of Rhodes, Greece, Europe

Palace of the Grand Master of the Knights of Rhodes, historic town centre of the city of Rhodes, Rhodes, Greece, Europe