Ashley Cooper / La Calahorra Castle in La Calahorra at the foot of the Sierra Nevada mountains in Andalucia, Spain,

Ashley Cooper / La Calahorra Castle in La Calahorra with spring flowers, at the foot of the Sierra Nevada mountains in Andalucia, Spain.

Oriol Alamany / Fortified city of Dalt Vila, Ibiza city, Ibiza biodiversity and culture UNESCO World Heritage Site, Spain.

Pascal Kobeh / Aerial view of Tulum a Mayan a fortified city of the 10th century located near the sea, Yucatan peninsula, Mexico

Juergen Freund / Aerial of Port Denarau Island Resort, Viti Levu, Fiji. December 2013.

Steve O. Taylor (GHF) / Large fortified cave, home to ancient cave paintings and battle mural, Guilemsi, central Mauritania, 2004.

Gavin Hellier / Sighisoara, medieval Old Town or citadel, the clock tower (Turnul cu Ceas), formarly the main entrance to the fortified city the tower is 64m tall, inside the 1648 clock is a pageant of slowly revolvi...

Benoit Stichelbaut / Fortified city of Saint Malo, Brittany, France

Benoit Stichelbaut / Fishing boats moored alongside jetty in Concarneau, Finistere, Brittany, France

David Woodfall / Fortified 12th century Saxon village church, important to protect region from Ottoman Empire, helping it to remain traditional peasant community. Romania, October 2010

Juan Carlos Munoz / Interior of Mousa Broch, ancient fortified stone tower, Mousa Island, Shetland Islands, Scotland, UK

Juan Carlos Munoz / Interior of Mousa Broch, ancient fortified stone tower, Mousa Island, Shetland Islands, Scotland, UK

Juan Carlos Munoz / Interior of Mousa Broch, ancient fortified stone tower, Mousa Island, Shetland Islands, Scotland, UK

Jouan & Rius / The fortified site of Clickimin Broch, west of the town of Lerwick, occupied from the 7th century BC to the 6th century AD, Mainland, Shetland Islands, Scotland, UK

Juan Manuel Borrero / Looking up at the high fortified walls of the Medina in Marrakech, Morocco December 2007

Jose B. Ruiz / Albarracin fortified village, Albarracin mountains, Teruel, Spain

Jose B. Ruiz / Fortified village in the Albarracin mountains, Teruel, Spain

Jose B. Ruiz / Fortified walls, Alcazaba, Malaga, Andalucia, Spain

Jose B. Ruiz / Fortified walls, Alcazaba, Almeria, Andalucia, Spain

Asgeir Helgestad / Fortified harbour of Rocca Scaligera, Sirmione, Lake Garda, Italy

Jose B. Ruiz / Flock of sheep grazing outside fortified walls of Alcazaba, Almeria, Andalucia, Spain

Jose B. Ruiz / Fortified walls of Alcazaba, Almeria, Andalucia, Spain

Jose B. Ruiz / Vilafames fortified village. Castellon, Spain, Europe

Jose B. Ruiz / Fortified church and village. Ujue, Navarra, Spain, Europe

Gavin Hellier / Panoramic view of Medieval fortified bridge and tower at Besalu, The Pont Fortificat, Catalunya, Spain

Gavin Hellier / Medieval 11th Century fortified bridge Basalu, Cataluya, Spain

Alex Hyde / View from Carl Wark, an Iron Age fortified hill, looking towards Higger Tor, Peak District National Park, Derbyshire, UK. September, 2010.

Ashley Cooper / Clickimin Broch, an Iron age fortified building, Lerwick, Shetland, Scotland, UK. June.

Fernando Faciole / Aerial view of Garcia d'Avila, second fortified residence in Brazil. Praia do Forte, Mata de Sao Joao, Bahia, Brazil. September, 2018.

Denis-Huot / Fortified village of Puycelsi, aerial view, Occitanie, France. May.

Will Watson / Hopton Castle, a 13th Century fortified tower house, and medieval moat carpeted with Pond water crowfoot (Ranunculus peltatus), Shropshire Hills Area of Outstanding Natural Beauty, England, UK. June,...

Philippe Clement / Hohenschwangau Castle, 19th-century palace and childhood residence of King Ludwig II of Bavaria at Hohenschwangau, Bavaria, Germany, October 2019

Philippe Clement / Hohenschwangau Castle, 19th-century palace and childhood residence of King Ludwig II of Bavaria at Hohenschwangau, Bavaria, Germany, October 2019

Philippe Clement / Hohenschwangau Castle, 19th-century palace and childhood residence of King Ludwig II of Bavaria at Hohenschwangau, Bavaria, Germany, October 2019

Philippe Clement / Ruins of the medieval Chateau de Montsegur castle on hilltop at sunset, stronghold of the Cathars, Ariege, Occitanie, France, September 2018

Philippe Clement / View over Scalloway Castle, museum and fishing boats in the harbour of the village Scalloway on the Mainland, Shetland Islands, Scotland, UK. June 2018

Philippe Clement / Castle Stalker, medieval four-story tower house / keep at sunset in Loch Laich, inlet off Loch Linnhe near Port Appin, Argyll, Scotland, UK. June 2018

Philippe Clement / Castle Stalker, medieval four-story tower house / keep at sunset in Loch Laich, inlet off Loch Linnhe near Port Appin, Argyll, Scotland, UK. June 2018

Philippe Clement / Citadel of the city Sisteron on the banks of the River Durance, Provence-Alpes-Cote d'Azur, Alpes-de-Haute-Provence, France. September 2018

Philippe Clement / Citadel and the city Sisteron on the banks of the River Durance, Provence-Alpes-Cote d'Azur, Alpes-de-Haute-Provence, France. September 2018