Jabruson / 'Kith' / 'Kin' Sumatran orangutan (Pongo abelii) captive animal in walled enclosure, Perth Zoo, Western Australia, August 2001.

Gavin Hellier / People commuting through glass walled passageway in modern building, Berlin, Germany, 2009. No release available.

Ernie Janes / Apricot tree (Prunus ameniaca) Moorpark variety in blossom trained against a wall in walled garden, UK, March.

Ernie Janes / Conference Pear tree (Pyrus communis) growing against wall in garden, UK

Nick Upton / Walled fields of Prickly pear / Barbary fig (Opuntia ficus-indica) on volcanic soil, formerly harvested for Cochineal insects (Dactylopius coccus), with Monte Corona volcanic peak in the background, n...

Ashley Cooper / Field terraces above a Berber village in the Anti Atlas mountains of Morocco, North Africa. April 2012. In recent years, rainfall totals have reduced by around 75% as a result of climate change.

Andres M. Dominguez / Bee hives kept in walled area to deter bears, Muniellos National Park, Asturias, Spain. October

Philippe Clement / Dun Telve broch near Glenelg, showing Iron Age drystone hollow-walled structure, Ross and Cromarty, Scottish Highlands, Scotland, UK, June 2017

Philippe Clement / Dun Telve broch near Glenelg, showing Iron Age drystone hollow-walled structure, Ross and Cromarty, Scottish Highlands, Scotland, UK, June 2017

Juan Manuel Borrero / Coast off the pre-Columbian Mayan walled city, Tulum, with the Castillo. Tulum National Park, Quintana Roo, Mexico.

Juan Manuel Borrero / Coast off the pre-Columbian Mayan walled city, Tulum, with Temple of the God of Wind. Tulum National Park, Quintana Roo, Mexico.

Yva Momatiuk & John Eastcott / Domestic Sheep (Ovis aries) ewes and lamb in stone-walled pasture, Isle of Skye, Scotland

Ernie Janes / Clematis (Clematis montana) in flower growing over archway in walled garden, Norfolk, England, UK, June.

Gavin Hellier / People commuting through glass walled passageway in modern building, Berlin, Germany, 2009

Jean E. Roche / Aerial view of the walled city of Aigues-Mortes with the Charnier marshes in the background, Camargue, Southern France, November 2008

Benoit Stichelbaut / Saint Malo walled city, Brittany, France

Benoit Stichelbaut / Clock tower and harbour walls of the medieval walled fishing town of Concarneau in the mist. Brittany, France, July 2007.

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France

Benoit Stichelbaut / Beach beneath ramparts, Saint Malo, France

Benoit Stichelbaut / Boats moored in evening light, Concarneau, Finistere, Brittany, France

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

Benoit Stichelbaut / Punts moored in harbour, Concarneau, Finistere, Brittany, France

Benoit Stichelbaut / Beach beneath the ramparts of Saint Malo walled city, Brittany, France

Benoit Stichelbaut / Yachts in St Malo Harbour, France. Route du Rhum, November 2002

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France. April 2010.

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France. April 2010.

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France. April 2010.

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

Ernie Janes / Orange nasturtiums (Tropaeolum sp) growing in walled garden, Norfolk, UK, July

Ernie Janes / Red mason bee (Osmia rufa) nesting boxes in walled garden, UK

Ernie Janes / Rose arch and walled garden, Hoveton, Norfolk, UK

Piotr Naskrecki / Ant Plant (Hydnophytum sp) caudex with cross-section showing smooth-walled chambers that provide home for ants which leave behind their nutrient-rich waste products, Papua New Guinea, composite image

Ernie Janes / Path through a walled cottage garden in summer with flowering poppies, foxgloves and clematis, Binham, Norfolk, UK

Ernie Janes / Path through a walled cottage garden in summer with flowering foxgloves and poppies, Binham, Norfolk, UK

Ernie Janes / Penstemons flowering in herbaceous flowerbed in walled garden, Claydon house, Buckinghamshire, UK

Ernie Janes / Walled garden at Blickling Hall, Norfolk, UK, July

Philippe Clement / View of the walled city Saint-Malo, Brittany, France. September 2010.

Nick Upton / Medieval walled citadel of Calvi viewed from the sea at dawn with mountainous backdrop. Corsica, France, May 2010.

Nick Upton / Medieval walled citadel of Calvi below snow covered peaks of the 2000m high Monte Padro ridge in dawn light. Corsica, France, May 2010.

Benoit Stichelbaut / Concarneau, Finistere, Brittany, France. April 2010.

Richard Du Toit / Walled townhouse complex showing dense suburban development, Pretoria, South Africa

Gary K. Smith / Horseradish {Armoracia rusticana} cultivated for culinary use in a large walled garden, Norfolk, UK, July,

Gary K. Smith / Cordon Pear (Pyrus communis) variety 'Cattilac' ripening fruit growing in walled garden, England, UK, August

Gary K. Smith / Pear (Pyrus communis) variety 'Vicar of Winkfield' ripening fruit growing in walled garden, England, UK, August

Gary K. Smith / Cordon Pear (Pyrus communis) variety 'Conference' ripening fruit growing in walled garden, England, UK, August

Gary K. Smith / Cordon Pear (Pyrus communis) variety 'berre clairgeau' in walled garden, England, UK, August

David Cottridge / Face of house in old walled city of Sana'a, Yemen

David Cottridge / Looking across buildings in old walled city of Sana'a, Yemen

Ernie Janes / Quiet corner of a walled garden with two seats, East Rushton, Norfolk, UK

Graham Eaton / Remains of a hut circle with a clear entrance within the walled enclosure of Grimspound, a late Bronze Age settlement, Dartmoor, Devon, England. January, 2022.

Graham Eaton / Remains of a hut circle with a clear entrance within the walled enclosure of Grimspound, a late Bronze Age settlement, Dartmoor, Devon, England. January, 2022.

Neil Aldridge / Conversion of traditional stone-walled barns, here earmarked for development, into countryside homes, Cornwall, England. December.