Kirkendall-Spring / Doorway of the poet Dilgo Khyentse Rinpoche's house, near Paro, Bhutan, October 2014.

TJ Rich / Young springer spaniel sitting on doorstep. Wiltshire, England, UK.

Ashley Cooper / House surrounded by flood waters by the banks of the River Rothay in Ambleside, in the Lake District on Saturday 5th December 2015, during torrential rain from storm Desmond. England, UK, December 201...

Ashley Cooper / Polar bear (Ursus maritimus) skin killed by an inuit hunter in Ilulissat, Greenland, July 2008.

Franco Banfi / Local woman sitting in front of her house, Camaguey, Cuba, Caribbean Sea, Atlantic Ocean. November 2007.

Aflo / Black cat sitting in front of blue door.

Iris Thorsteinsdottir / Siberian forest cat (Felis catus) grey, ginger and white female kitten age 7 Months sitting by door. Clifton, Bristol, UK.

David Noton / Blue doorway with Grape vines (Vitis) Puyloubier, Var, Provence, France, October 2012.

Ross Hoddinott / Long exposure waves on beach in front of Durdle Door in late evening light, Dorset, UK, April 2013.

David Woodfall / Flooding outside house with debris in front of door during February 2014 floods, Upton upon Severn, Worcestershire, England, UK, 9th February 2014.

Pat Tuson / Old door in front of skip offered for recycling with a note saying Please Help Yourself, Highbury, London Borough of Islington, UK

Pat Tuson / Old door in front of skip offered for recycling with a note saying Please Help Yourself, Highbury, London Borough of Islington, UK