Sven Zacek,Sven Zacek / Kopu lighthouse - the oldest lighthouse in Estonia, on Hiiumaa island. August 2011.

Gavin Hellier / Cobbled street lined with colourful houses known as Kujundziluk, one of the oldest streets in Mostar leading to the Old Bridge, Old Town, Mostar, Herzegovina, Bosnia and Herzegovina, Balkans, 2007. No...

Danny Green / 2020VISION / Wigeon (Anas Penelope) on estuary mud stretching wings, Caerlaverock WWT, Scotland, Solway, UK, January. Did you know? The oldest known wigeon lived to 34 years old.

Wild Wonders of Europe / Radisics / Oak tree, the oldest tree in Hortobagy National Park, Hungary, July 2009

Kevin Schafer / Great Basin Bristlecone Pine (Pinus longaeva), White Mountains, California

Mark Brownlow / Rebreather instructor Ian Thomas and cameraman Didier Noirot prepare to dive under the ice, Lake Baikal, world's deepest and oldest (and largest by volume) freshwater lake, Siberia, Russia. BBC Plane...

Mark Brownlow / Looking down on frozen surface of Lake Baikal, world's deepest and oldest (and largest by volume) freshwater lake, Siberia, Russia. BBC Planet Earth series, April 2005

Mark Brownlow / Mark Brownlow, producer of Freshwater programme for BBC Planet Earth series, behind ice sheet, on location at Lake Baikal, world's deepest and oldest (and largest by volume) freshwater lake, Siberia,...

Hiroya Minakuchi / Stromatolites, the oldest life form that still exists today, Hamelin Pool, Shark Bay, Western Australia

Jim Brandenburg / Giant Sequoia (Sequoiadendron giganteum) forest, King's Canyon National Park, California

Mitsuaki Iwago / Stromatolites, the oldest life form that still exists today, Shark Bay, Australia

Fred Bavendam / Stromatolites, colonies of blue-green algae, the oldest life form that still exists today fossils dated to over three billion years ago, Hamelin pool, Western Australia