Yellow rendering on stonework conservation project, Orford Castle, Suffolk, England, United Kingdom, Europe

The Barbican, UNESCO World Heritage Site, Warsaw, Poland, Europe

Norman-Swabian Castle, Barletta, Barletta-Andria-Trani, Apulia, Italy

Medieval brick castle, Turaida Museum Reserve, Sigulda,Gauja National Park, Vidzeme Region, Latvia, Baltic region, Europe

Medieval brick castle overhanging the Gauja River, Turaida Museum Reserve, Sigulda,Gauja National Park, Vidzeme Region, Latvia, Baltic region, Europe

Quaint street with historic architecture and clear blue sky in Canterbury, Kent, England, United Kingdom, Europe

Old city walls, entrance to historic castle site, Cuenca, Castille La Mancha, Spain, Europe

Medieval town walls and spire of St. Olav's church at dusk, Tallinn, Estonia, Baltic States, Europe

Historic architecture in Edinburgh with the Hub and spires against a cloudy sky, showcasing Scotland's capital city's charm, Edinburgh, Scotland, United Kingdom, Europe

Medieval town walls and spire of St. Olavs church at dusk, Tallinn, Estonia, Baltic States, Europe

Sforza Castle medieval tower, 15th century Castello Sforzesco fortified round tower, Milan, Lombardy, Italy, Europe

Bran Castle, Bran, near Brasov, Transylvania. The castle was built by Saxons in 1377 who were given the privilege by Louis I of Hungary. It is a national monument and landmark in Transylvania and famous for its association with the Dracula story

West facade of the Chateau de Maintenon, Eure-et-Loir department, Centre-Val de Loire region, France, Europe

Palace of the Popes, Avignon, UNESCO World Heritage Site, Vaucluse, Provence-Alpes-Cote d'Azur, France, Europe

Castello Estense, Ferrara, Emilia Romagna, Italy, Europe

Medieval castle of Grinzane Cavour in vineyards, Province of Cuneo, Piedmont region, Italy, Europe

Torre Astura medieval castle seen from an arch made of bricks, Tyrrhenian Sea, Rome province, Latium (Lazio), Italy, Europe

Medieval town walls, defence towers and spire of St. Olav's church at sunset, Tallinn, Estonia, Baltic States, Europe

Wooden bridge leading to the Trakai Castle on an island in Lake Galve, Lithuania, Europe

A Medieval granary of oak frame and brick infill, set on toadstools to prevent access by rats, Cowdray Castle, Midhurst, West Sussex, England, United Kingdom, Europe

Norman Keep, Cardiff Castle, Cardiff, Wales

Castle of the Teutonic Knights in Malbork (13th - 14th century), Poland

Ghorfas, storage rooms, Berber granary Qasr-al-Hadj, Nafusah Mountains, Libya

Yard of Turaida Castle, bishop's castle, Gauja river, Turaida, Latvia, Baltic States, Northern Europe

Chateau Saint-Maire, Lausanne, canton of Vaud, Lake Geneva, Switzerland, Europe

Malbork Castle with Nogat, Malbork, Pomerania, Poland, Europe

Chateau Saint-Maire, Lausanne, canton of Vaud, Lake Geneva, Switzerland, Europe

Keep with bishop's castle, Turaida Castle, Turaida, Latvia, Baltic States, Northern Europe

Keep with bishop's castle, Turaida Castle, Turaida, Latvia, Baltic States, Northern Europe

Malbork Castle with Nogat, Malbork, Pomerania, Poland, Europe

Medieval village of Ricetto di Candelo used as a refuge in times of attack during the Middle Age, Biella, Piedmont, Italy, Europe