Porte d'Aude, entrance to walled and turreted fortress of Cite, Carcassonne, UNESCO World Heritage Site, Languedoc, France, Europe

Snow covered rocky moorland landscape overlooking the Bronze Age walled settlement of Grimspound, Dartmoor National Park, Devon, England, United Kingdom, Europe

Rice terraces typical of Ifugao culture, Kapayaw, near Sagada, Cordillera, Luzon, Philippines, Southeast Asia, Asia

Villager walking across rice terraces typical of Ifugao culture, Aguid, near Sagada, Cordillera, Luzon, Philippines, Southeast Asia, Asia

Historic walled defences to Moorish citadel fortress palace of the Alcazaba, Malaga, Andalusia, Spain, Europe

Historic walled defences to Moorish citadel fortress palace of the Alcazaba, Malaga, Andalusia, Spain, Europe

Dawn on the stone walls of The Cobb, Lyme Regis, Dorset, England, United Kingdom, Europe

Stone walled city and St. Paul's Cathedral, Mdina, Malta, Mediterranean, Europe

Mdina Gate with horse drawn carriage, Mdina, Malta, Mediterranean, Europe

Historic walled castle in hilltop village of Monsaraz, Alto Alentejo, Portugal, Europe

Historic walled castle in hilltop village of Monsaraz, Alto Alentejo, Portugal, Europe

Muscat Gate Museum, straddles the road between Mutrah Corniche and old walled city, Muscat, Oman, Middle East

Sant Pere church and stone houses in gorgeous medieval hilltop walled village, Pals, Baix Emporda, Girona, Catalonia, Spain, Europe

Corner tower and moats of the ancient walled city of Chiang Mai, Thailand, Southeast Asia, Asia

Walled and turreted fortress of Cite, Carcassonne, UNESCO World Heritage Site, Languedoc, France, Europe

Walled village, Kam Tin, Hong Kong, China, Asia

Steep and narrow winding street in gorgeous medieval hilltop walled village, Pals, Baix Emporda, Girona, Catalonia, Spain, Europe

Old lady selling embroidery in the walled medieval town of Obidos, declared national monument, Estremadura, Portugal, Europe

The Clock Tower, Old Walled City District, Cartagena City, Bolivar State, Colombia, South America

Entrance to Chateau Comtal in the walled and turreted fortress of La Cite, Carcassonne, UNESCO World Heritage Site, Languedoc, France, Europe

Entrance to Chateau Comtal in the walled and turreted fortress of La Cite, Carcassonne, UNESCO World Heritage Site, Languedoc, France, Europe

Traditional slate walled cottages at Seatoller, Borrowdale, Lake District National Park, Cumbria, England, United Kingdom, Europe

The Terrace of the Elephants, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Terrace of the Leper King, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Terrace of the Leper King, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Terrace of the Elephants, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Terrace of the Elephants, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Main gate with moat, garden and ramparts, Mdina, a Medieval walled city, Mdina, Malta, Europe

Glenveagh castle in the Glenveagh National Park, County Donegal, Ulster, Republic of Ireland, Europe

Bleak flat landscape of stone-walled farms, Inishmaan, Aran Islands, County Galway, Connacht, Republic of Ireland, Europe

Tower with two of the 216 smiling sandstone faces at 12th century Bayon temple in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

Towers and three of the 216 smiling sandstone faces at 12th century Bayon temple in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

Towers of the famous Bayon, last temple built by King Jayavarman VII in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

West inner gallery towers and seven of the 216 carved faces at Bayon temple in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

Yama, Hindu God of Death, Terrace of the Leper King, Royal Square of the Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

View east from upper terrace of restored 11th century Baphuon pyramid temple in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

West inner gallery towers and four of the 216 carved faces at Bayon temple in Angkor Thom walled city, Angkor, UNESCO World Heritage Site, Siem Reap, Cambodia, Indochina, Southeast Asia, Asia

Panoramic view of Saint-Malo’s historic walled city and seafront ramparts, Brittany, France, with waves against the stone walls

panoramic view of Saint-Malo walled city and harbor from stone pier in Brittany France

Panoramic coastal view of Saint-Malo walled city with spire and stone ramparts Brittany France. Coastal walkway of Dinard in the foreground

The Terrace of the Elephants, part of the walled city of Angkor Thom, a ruined temple complex in Angkor, UNESCO World Heritage Site, Cambodia, Indochina, Southeast Asia, Asia

The Walled City (Ciudad Amurallada), UNESCO World Heritage Site, Cartagena, Colombia, South America

The Walled City (Ciudad Amurallada), UNESCO World Heritage Site, Cartagena, Colombia, South America

Stone walled fields and farm buildings in valley, Swaledale, Yorkshire Dales National Park, Yorkshire, England, United Kingdom, Europe

Torana (arched gateway) of the walled Jain temples at Lodrapur, Rajasthan state, India, Asia

Aerial views of El Castillo and the Ruins of the Mayan temple grounds at Tulum, Quintana Roo, Yucatan, Mexico. Tulum is the site of a pre-Columbian Mayan walled city which served as a major port for Coba, in the Mexican state of Quintana Roo. The ruins are situated on 12 meter 39 ft tall cliffs along the east coast of the Yucatán Peninsula on the Caribbean Sea in the state of Quintana Roo, Mexico. Tulum was one of the last cities built and inhabited by the Maya; it was at its height between the 13th and 15th centuries and managed to survive about 70 years after the Spanish began occupying Mexico. Old World diseases brought by the Spanish settlers appear to have resulted in very high fatalities, disrupting the society, and eventually causing the city to be abandoned.

Aerial views of El Castillo and the Ruins of the Mayan temple grounds at Tulum, Quintana Roo, Yucatan, Mexico. Tulum is the site of a pre-Columbian Mayan walled city which served as a major port for Coba, in the Mexican state of Quintana Roo. The ruins are situated on 12 meter 39 ft tall cliffs along the east coast of the Yucatán Peninsula on the Caribbean Sea in the state of Quintana Roo, Mexico. Tulum was one of the last cities built and inhabited by the Maya; it was at its height between the 13th and 15th centuries and managed to survive about 70 years after the Spanish began occupying Mexico. Old World diseases brought by the Spanish settlers appear to have resulted in very high fatalities, disrupting the society, and eventually causing the city to be abandoned.

Buildings used as store rooms at the Citadel of Qaitbay, also known as Fort of Qaitbay, Alexandria, Egypt

U Min Thonze Pagoda, Sagaing, near Mandalay, Myanmar, (Burma)

Lakeland hills reflecting on the still water of Thirlmere Reservoir, Lake District National Park, Cumbria, England

Thirlmere Reservoir, Lake District National Park, Cumbria, England

Grimaud Castle, Grimaud, Cote D,??Azur, France

Remains of ancient fortress walls, Nessebar, Bulgaria

Remains of ancient fortress walls, Nessebar, Bulgaria

Rabat I Malik Caravanserai, also known as Raboti Malik Caravanserai, Navoi Province, Uzbekistan

The port of Goury on the Cotentin Peninsula, Normandy, France in a storm. Old stone walls in the foreground.

Walled Old City of Dubrovnik, Croatia

Walled Old City of Dubrovnik, Croatia

Walled Old City of Dubrovnik, Croatia

Cobblestone street, medieval walled town of Perouges, France, Europe

Cobblestone street, medieval walled town of Perouges, France, Europe

Place de la Halle square, medieval walled town of Perouges, France, Europe

Cobblestone street, medieval walled town of Perouges, France, Europe

Cobblestone street, medieval walled town of Perouges, France, Europe

Cobblestone street, medieval walled town of Perouges, France, Europe

Typical stone roof cottages, walled town, Beynac-et-Cazenac, Dordogne, Aquitaine, France, Europe

Cobblestone street, medieval walled town of Perouges, France, Europe

Place de la Halle square, medieval walled town of Perouges, France, Europe

Tourists in San Gimignano, a small walled medieval hill town in the province of Siena, Tuscany, north-central Italy. Known as the Town of Fine Towers, San Gimignano is famous for its medieval architecture, unique in the preservation of about a dozen of its tower houses, which, with its hilltop setting and encircling walls

Landscape With Lough Corrib In The Distance, County Galway, Ireland

Grenoble, Isère, France, Window Of An Old Stone-Walled European House

Greece, Attica, Athens, Hadrians Library.

Greece, Attica, Athens, Odeon of Herodes Atticus, located on southwest slope of the Acropolis.

Greece, Attica, Athens, Odeon of Herodes Atticus, located on southwest slope of the Acropolis.

Inca Ingapirca, north of Cuenca, is Ecuador's greatest Inca archaeological site finely cut walls of the Sun Temple rise above landscape, Highlands, Ecuador

Inca Ingapirca, north of Cuenca, is Ecuador's greatest Inca archaeological site Sun Temple was main structure in the fortified Inca town, Highlands, Ecuador

Inca Ingapirca, north of Cuenca, is Ecuador's greatest Inca archaeological site Sun Temple was main structure in the fortified Inca town, Highlands, Ecuador

Inca Ingapirca, north of Cuenca, is Ecuador's greatest Inca archaeological site Sun Temple was main structure in the fortified Inca town, Highlands, Ecuador