Crenellated tower, XIII c., Torre di Palme, Fermo, Ascoli Piceno, Marche, Italy

Basilica of Notre-Dame de Fourviere with its four crenellated octagonal towers, Lyon, France, Europe

Tower of Mangana (Torre Mangana), on site of Moorish city, Cuenca, Castille La Mancha, Spain, Europe

View of cafe and Museo Casa Rossa di Anacapri, Anacapri, Isle of Capri, Campania, Italy, Mediterranean, Europe

Old cannon, Skala of the Kasbah a mighty crenellated bastion, 300 metres in length, built on the cliffs to protect the city on its seaward side, Essaouira, historic city of Mogador, Morocco, North Africa, Africa

Palazzo Vecchio, Piazza della Signoria, Florence (Firenze), UNESCO World Heritage Site, Tuscany, Italy, Europe

Old cannons, Skala of the Kasbah a mighty crenellated bastion, 300 metres in length, built on the cliffs to protect the city on its seaward side, Essaouira, historic city of Mogador, Morocco, North Africa, Africa

Sandstone and marble gateway to 17th Century Tomb of Etimad Ud Doulah, 17th Century Mughal, tomb built 1628, Agra, India

Amar Singh Gate of Agra Fort, 17th Century residence of Great Mughals and Mughal fort in Agra, Northern India

Sandstone and marble gateway to 17th Century Tomb of Etimad Ud Doulah, 17th Century Mughal, tomb built 1628, Agra, India

Sandstone and marble gateway to 17th Century Tomb of Etimad Ud Doulah, 17th Century Mughal, tomb built 1628, Agra, India

Old cannons, Skala of the Kasbah a mighty crenellated bastion, 300 metres in length, built on the cliffs to protect the city on its seaward side, Essaouira, historic city of Mogador, Morocco, North Africa, Africa

Skala of the Kasbah, a crenellated bastion 300 metres in length, built on the cliffs to protect the city on its seaward side, Essaouira, historic city of Mogador, Morocco, North Africa, Africa

The Great Wall on the ridge tops above Mutinanyu, China.

Two Chinese men working on the restoration of the Great Wall at Mutianyu, China.

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

Chinese tourists looking at the landscape from the Great Wall at Mutianyu, China.

Two Chinese men working on the restoration of the Great Wall at Mutianyu, China.

Classic Chinese architecture in the tiled roof of a building in Mutianyu, China.

Classic Chinese architecture in the tiled roof of a building in Mutianyu, China.

Castle Castell de Capdepera, castellated battlement, Capdepera, Balearic Islands, Majorca

Majorca, Alcudia, flags on the top of a city gate

OMAN Muscat Muscat Gate Museum Crenellated gatehouse with archways over roads divided by central strip of grass with white tubs of red and white flowers.

Italy, Veneto, Venice, Centro Storico, Arsenale, Part view of crenellated tower flying Italian tricolour flag with statue of Neptune in foreground against clear blue sky of late summer

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

The Damascus Gate, Jerusalem, Israel

Tower of Mamure Castle in Anamur, Mersin Province, Turkey

Tower of Mamure Castle in Anamur, Mersin Province, Turkey

Entrance of Mamure Castle in Anamur, Mersin Province, Turkey