Ancient Theatre of Epidaurus, Greece (© George Pachantouris/Getty Images)

Château de Pierrefonds, France (© Hemis/Alamy)

Alpine marmots (© Michaela Walch/Alamy)

Chateau Frontenac, (© Romiana Lee/Shutterstock)

Feldberg Tower (© Hemis/Alamy)

Monarch butterflies (© Mimi Ditchie/Getty Images)

Fiordland National Park, South Island, New Zealand (© WitR/Adobe Stock)

Labro, Province of Rieti, Italy (© Marco Ilari/Shutterstock)

Eilean Donan Castle, Highlands, Scotland (© VisualCommunications/Getty Images)

Lower Antelope Canyon, Arizona, USA (© AZCat/Getty Images)

Milky Way over Zabriskie Point, California, USA (© Matt Anderson Photography/Getty Images)

Blue-footed booby, Galápagos Islands, Ecuador (© Tui De Roy/Minden Pictures)

Valley of the Moon, Chile (© Ignacio Palacios/Getty Images)

Igloo in Otaru, Hokkaido, Japan (© T Photography/Shutterstock)

Hippopotamus mother and baby, Chobe National Park, Botswana (© jacobeukman/Getty Images)

'Firefall' on Horsetail Fall, Yosemite National Park, California, USA (© Jeff Lewis/Tandem Stills + Motion)

Allen's hummingbird perched on a red kangaroo paw plant (© GypsyPictureShow/Shutterstock)

Eben Ice Caves, Upper Peninsula, Michigan, USA (© Dean Pennala/Shutterstock)

Humpback whales, Maui, Hawaii, USA (© Flip Nicklin/Minden Pictures)

Itaimbezinho canyon (© NidoHuebl/Getty Images)

French Quarter, New Orleans, Louisiana, USA (© f11photo/Getty Images)

Peace bell on the summit of Fichtelberg, Saxony, Germany (© Jan Drahokoupil/Getty Images)

Croesor Valley, Snowdonia National Park, Wales, UK (© Matthew Williams-Ellis/Plainpicture)

Mandarin duck, Richmond Park, London, UK (© Oscar Dewhurst/Minden Pictures)

Hoodoos at Bryce Canyon National Park in Utah, USA (© Piriya Photography/Getty Images)

Canopy adventure in the Peruvian Amazon, Tambopata National Reserve, Peru (© Pere Rubi/Getty Images)

Polar bears asleep in Canada (© David Pike/Minden Pictures)

Atrani, Amalfi Coast, Italy (© Amazing Aerial/Shutterstock)