Aerial image of Yarnbury Castle, a hill fort, in snow, Wiltshire, England, United Kingdom, Europe

Aerial image of Danebury Ring, an Iron Age hill fort, Wiltshire, England, United Kingdom, Europe

Aerial image of Battlesbury Camp, an Iron Age Hill fort, Warminster, Wiltshire, England, United Kingdom, Europe

Fasiladas' Palace, The Royal Enclosure, Gonder, Ethiopia, Nortern Ethiopia, Africa

Fasiladas' Palace, The Royal Enclosure, Gonder, Ethiopia, Nortern Ethiopia, Africa

Aerial image of Bury Hill Fort, Wiltshire, England, United Kingdom, Europe

Naveta d'Es Tudon, megalithic chamber tomb, 1130-820 BC, Menorca, Balearic Islands, Spain, Mediterranean, Europe

Traditional dry stone wall, vertical sloping stones, in field in The Burren, County Clare, West of Ireland

Pair of adult llamas, one male one female, at Ferme de l'Eglise, Normandy, France

Traditional dry stone wall in meadow in The Burren, County Clare, West of Ireland

Traditional dry stone wall in meadow in The Burren, County Clare, West of Ireland

Traditional dry stone wall and meadow in The Burren, County Clare, West of Ireland

Traditional dry stone wall and meadow in The Burren, County Clare, West of Ireland

Traditional dry stone wall in meadow in The Burren, County Clare, West of Ireland

Traditional dry stone wall, stones laid flat, in field in The Burren, County Clare, West of Ireland

Two rams in a grassy field, one standing alert and the other grazing, Mouflon (Ovis gmelini), Wildpark Aurach, Austria, Europe

Fence in the floodplains of Neufelder Koog, polder, Elbe estuary, North Sea coast, Schleswig-Holstein Wadden Sea National Park, Dithmarschen region, Schleswig-Holstein, Germany, Europe

Playground for ball games, Nuremberg, Franconia, Bavaria, Germany

Lone bull in a fenced in enclosure on the Prairies - Southern Saskatchewan, Canada

Reindeer preparing to come out of their enclosure to spend the day in the surrounding taiga for food, around Uoyan, Buryatia, Russia

Reindeer coming out of the enclosure to spend the day in the surrounding taiga to feed, around Uoyan, Buryatia, Russia

Reindeer coming out of the enclosure to spend the day in the surrounding taiga to feed, around Uoyan, Buryatia, Russia