Andy Goldsworthy's 'Wood Line' installation near Lovers' Lane in the Presidio of San Francisco, California (© Chris LaBasco/Alamy)

Sky Rock petroglyphs in the Volcanic Tablelands near Bishop, California (© JTBaskinphoto/Getty Images)

Polar bears in Torngat Mountains National Park, Canada (© Cavan Images/Offset by Shutterstock)

The United States Capitol Building in Washington, DC (© f11photo/Getty Images)

Caribou swimming across Alaska's Kobuk River during fall migration (© Michio Hoshino/Minden Pictures)

Albarracín, Spain (© Domingo Leiva/Getty Images)

West Indian manatees in Three Sisters Springs, Crystal River National Wildlife Refuge, Florida (© Norbert Probst/Getty Images)

Bison in Grand Teton National Park, Wyoming (© Brian Evans/Getty Images)

Derwent Island on Derwentwater in the Lake District National Park, Cumbria, England (© Chris Warren/eStock Photo)

Vineyards near Barolo, Piedmont, Italy (© Marco Arduino/eStock Photo)

Badlands National Park, South Dakota (© Dennis Frates/Alamy)

The Korean War Veterans Memorial, Washington, DC (© Ian G Dagnall/Alamy)

Connery Pond and Whiteface Mountain in New York state (© Henk Meijer/Alamy)

Ravens in a snowstorm near Kuhmo, Finland (© Frans Lemmens/Alamy)

Oil lamps being arranged on rangoli designs during Diwali (© Subir Basak/Getty Images)

Lupines on the shores of Lake Tekapo in New Zealand (© Stanislav Kachyna/Shutterstock)

The interior of the Great Temple at Abu Simbel, Egypt (© George Steinmetz/Getty Images)

Interior view of the Steven F. Udvar-Hazy Center, Smithsonian National Air and Space Museum in Chantilly, Virginia (© Rebecca Wyatt/Offset by Shutterstock)

Chestnut-mandibled toucan nesting in the cavity of a tree, Costa Rica (© Greg Basco/Minden Pictures)

Aerial view of the Aiguille du Midi in the Mont Blanc massif, France (© Amazing Aerial Agency/Offset by Shutterstock)

Autumn leaves frozen in ice, Price Lake, Julian Price Memorial Park, Blue Ridge Parkway, North Carolina (© Richard Bernabe/Offset by Shutterstock)

Common cranes in the Drömling wetland, Germany (© Mike Friedrichs/Getty Images)

Old Town of Bern, Switzerland (© Simon Zenger/Alamy)

Huge waves crashing on rocks along Asilomar State Beach, Pacific Grove, California (© Sheila Haddad/Danita Delimont)

A grove of American elm trees at Central Park's Mall, New York City (© AWL Images/Danita Delimont)

A Siberian chipmunk on Mount Taisetsu, Hokkaido, Japan (© Ida Toshiaki/Minden Pictures)

Kayaking in Glacier National Park, Montana (© Makayla Crist/Cavan)

Partly snow-covered slope in Val Cervara, an old-growth beech forest, Abruzzo, Italy (© Bruno D'Amicis/Minden Pictures)

Mount Taranaki, Egmont National Park, North Island, New Zealand (© Francesco Vaninetti/plainpicture)

Eilean Donan Castle in Scotland (© CBW/Alamy)