860-290890 - Sentinel, Andy Goldsworthy, 1999, Col du Defens, Alpes de haute Provence, France "The work Sentinels, which is part of the Refuge d'art project, is a journey through the Dignois region, at the foot of the Southern Alps. Such a project associates art, nature and the territory. The three Sentinels are stone cairns, one for each of the three valleys of the Haute-Provence Geological Reserve.

1116-51966 - Black rhinoceros (Diceros bicornis) standing on rocks lowering head and looking at camera in the Etosh National Park; Otavi, Oshikoto, Namibia

832-392924 - Meadow Brown (Maniola jurtina) on Meadow cranesbill (Geranium) (Geranium pratense) Hesse, Germany, Europe

832-392925 - Meadow Brown (Maniola jurtina) on Meadow cranesbill (Geranium) (Geranium pratense) Hesse, Germany, Europe

832-390391 - King and Queen, Chessboard

832-390390 - Checkers on a checkerboard

832-388577 - Marbled white (Melanargia galathea) sits on orchid (orchis), Bavaria, Germany, Europe

857-95438 - Smashed concrete sea defenses at Ulrome near Skipsea on Yorkshires East Coast, UK. The sea has eroded past the barriers and left them stranded further down the beach. The coast is composed of soft boulder clays, very vulnerable to coastal erosion. This section of coast has been eroding since Roman times, with many villages having disappeared into the sea, and is the fastest eroding coast in Europe. Climate change is speeding up the erosion, with sea level rise, increased stormy weather and increased heavy rainfall events, all playing their part.

1178-8503 - Defenses at Vicksburg National Military Park

911-10540 - The remains of Kirkoswold Castle in the Eden Valley, Cumbria, UK.

797-10858 - England, Hampshire, Milford on Sea, Second world war defences at Hurst Castle to defend the strategically important Solent.

797-10859 - England, Hampshire, Milford on Sea, Second world war defences at Hurst Castle to defend the strategically important Solent.

832-304401 - Old canon aimed in the direction of Cerro Santa Lucia Park and modern high-rises, Santiago de Chile, Chile, South America

832-291543 - Typical Albanian bunkers in the Vjoses valley, Aoos, with the Nemercke Mountain Range, Albania, Europe

842-304 - Sea defenses on the pebbly beach at Sheringham, Norfolk, England, United Kingdom, Europe

832-238887 - Cannon in the Turkish fort of Larnaka, Larnaca, Southern Cyprus, Cyprus, Europe

832-199346 - Storm surge barrier, Delta Works, Zeeland, Holland, Netherlands, Europe

832-199345 - Storm surge barrier, Delta Works, Zeeland, Holland, Netherlands, Europe

832-177938 - Cannons in front of the fortress, Pula, Istria, Croatia, Europe

832-177937 - Cannons in front of the fortress, Pula, Istria, Croatia, Europe

832-177939 - Cannons in front of the fortress, Pula, Istria, Croatia, Europe

832-114097 - Cannon on the ramparts of Saint Malo in Brittany, France, Europe

832-117758 - Gatehouse with an old cannon at Valdemars Castle, Svendborg, Funen, Denmark, Europe

832-82741 - Burg Reichenstein castle, Trechtingshausen, UNESCO World Heritage Site Upper Middle Rhine Valley, Rhineland-Palatinate, Germany, Europe

832-85046 - Old cannon, Karni Fort Bambora Palace Hotel, Rajasthan, India, Asia

1116-2195 - Dunree Fort, Lough Swilly, Inishowen Peninsula, County Donegal, Ireland

915-567 - Cardiff Bay Barrage, Cardiff, Wales, UK, Europe

915-569 - Cardiff Bay Barrage, Cardiff, Wales, UK, Europe

915-570 - Cardiff Bay Barrage, Cardiff, Wales, UK, Europe

915-568 - Cardiff Bay Barrage, Cardiff, Wales, UK, Europe

797-8212 - England, West Sussex; Bognor Regis, Wooden groynes at low tide used as sea defences against erosion of the shingle pebble beach seen through metal railings with colourful flags on the pier.

832-8192 - Mexican Burrowing Toad (Rhinophrynus dorsalis), adult bloated as defense, Starr County, Rio Grande Valley, Texas, USA

832-8193 - Mexican Burrowing Toad (Rhinophrynus dorsalis), adult bloated as defense, Starr County, Rio Grande Valley, Texas, USA

799-578 - Weathered wooden coastal defenses on Bossington Beach, Exmoor National Park, Somerset, England, United Kingdom, Europe

799-579 - Wooden groyne sea defenses on Bossington Beach at sunset, Exmoor National Park, Somerset, England, United Kingdom, Europe

799-679 - Wooden groyne coastal defenses at Porlock Beach, Exmoor National Park, Somerset, England, United Kingdom. Europe

763-63 - Castillo El Morro, built between 1589 and 1630 to protect Havana's harbor, lighthouse was built in 1845 seen from the Malecon, Habana Vieja, Havana, Cuba