George Chan / Old Muslim man, of non-Chinese ethnic minority, in Hotan (Hetian) City, on the ancient Silk Road, Xinjiang Province, North-west China. BBC Wild China: Prog 4. - Beyond the Great Wall. July 2006.

George Chan / The western end of the Great Wall of China, near Jiayuguan, Gansu Province, North-west China. June 2007, BBC "Wild China" series

George Chan / Yuguan Fortress at the end of the Great Wall, Gansu Province, North-west China. June 2007, BBC "Wild China" series

Gary K. Smith / Coastal car park flooded by water from freshwater marsh, sea wall in background, North Norfolk, UK

Gary K. Smith / Coastal car park flooded by water from freshwater marsh, sea wall in background, North Norfolk, UK

Kirkendall-Spring / Rocks in the surf at Hole-in-the-Wall on the Pacific Coast, Olympic NP, Washington, USA

Philippe Clement / Western Black widow (Latrodectus hesperus) spider on wall of building. Arizona, USA

Nick Garbutt / Maiden-hair Spleenwort {Aspleenium trichomanus} growing on wall, Isle of Mull, north west Scotland

Kirkendall-Spring / Sunset at the Hole-in-the-Wall, pacific coast, Olympic National Park, Washington, USA

Bernard Castelein / Mani wall, north of Ghami, Mustang, Nepal

Bernard Castelein / Mani wall, north of Ghami, Mustang, Nepal

Jack Dykinga / Snow covered Ponderosa Pines (Pinus ponderosa) with wall of Taft Point behind, Yosemite Valley, Yosemite National Park, California

Jack Dykinga / Sunrise reflected off canyon wall onto moist sand at base of National Canyon, Grand Canyon NP, Arizona, USA

Jack Dykinga / Sand sunflowers {Helianthus anomolus} flowering against canyon wall, Grand Staircase - Escalante National Monument, Utah, USA

Doug Allan / Inuit builds a snow wall round his tent for storm protection, Admiralty Inlet, Baffin Island, Canadian Arctic

GEORGETTE DOUWMA / Ochre sea stars {Pisaster ochraeceus} and Giant green anemones {Anthopleura xanthogrammica} exposed on rock wall during low tide, Olympic National Park, Washington, USA.

GEORGETTE DOUWMA / Ochre sea star {Pisaster ochraeceus} exposed on rock wall at low tide, Olympic National Park, Washington, USA.

GEORGETTE DOUWMA / Ochre sea stars {Pisaster ochraeceus} exposed on rock wall at low tide, Olympic National Park, Washington, USA.

GEORGETTE DOUWMA / Moorish idol {Zanclus cornutus} swimming past coral reef wall, Bunaken, North Sulawesi, Indonesia.

Jason Smalley / Wall of Ancient building made from mud bricks, El Bawiti, Egypt.

Staffan Widstrand / Ancient stone carvings, Luxor temple, Egypt.

Tom Vezo / Gambel's quail, male and female on wall {Callipepla gambelii} Arizona, USA.

Bob Barbour / Kieran Horn, off-the-wall, Oahu, Hawaii

Yva Momatiuk & John Eastcott / California Condor (Gymnogyps californianus) adult perched on canyon wall drying wings, with radio transmitter attached, Marble Canyon, Arizona

Norbert Wu / French Angelfish (Pomacanthus paru) along coral wall, Saba, Caribbean

Norbert Wu / Eroded sandstone and light in Antelope Canyon, Arizona

Fred Bavendam / Sea Star (Leiaster sp) crawling among Stony Coral (Tubastraea sp) on a reef wall, Manado, North Sulawesi, Indonesia

Fred Bavendam / Bannerfish (Heniochus diphreutes) school, 45 meters deep on a reef wall swimming past a large Sponge and Crinoids, Manado, North Sulawesi, Indonesia

Fred Bavendam / Spine-cheek Anemonefish (Premnas biaculeatus) living on a Bulb Tentacle Sea Anemone (Entacmaea quadricolor) on a reef wall, Manado, Indonesia

Fred Bavendam / Giant Green Sea Anemone (Anthopleura xanthogrammica) trio in tide pool, browning wall, British Columbia, Canada

GEORGETTE DOUWMA / Fossil coral building blocks used in Soakin, Sudan Democratic Republic, N Africa

Onne van der Wal / 12 Metre Heritage, built in 1970 races under the Newport Bridge during the Wall Street Challenge, Rhode Island, USA

Roberto Rinaldi / A school of anthias (Anthias sp) swimming over soft coral reef on the impressive wall of Ras Mohammed, protected by the Ras Mohammed National Marine Park, southern Sinai Peninsula, Egypt

Robert Thompson / Close up of stone in limestone dry stone wall, Killenmacoog, North Burren, County Clare, Republic of Ireland. July 2007.

Yva Momatiuk & John Eastcott / Cottonwood tree branches against sandstone walls, Grand Staircase-Escalante National Monument, Utah

Sumio Harada / Mountain Goat (Oreamnos americanus) female resting in snow with back against a rock wall for protection, Rocky Mountains, North America