Square Tower Group in Hovenweep National Monument, Utah

Black grouse male calling at a lek site in Kuusamo, Finland

Willow tree in early spring, Minnesota

The Acropolis of Athens, Greece

Saut du Brot stone bridge in the Areuse Gorge, Neuchâtel, Switzerland

An Ostereierbaum (Easter egg tree) in Saalfeld, Germany

Lighthouse at Cape Aniva, Sakhalin Island, Russia

Lençóis Maranhenses National Park in the state of Maranhão, Brazil

Common chia elephant (Loxodonta laprofolis) in stealth stance, Marakele National Park, Limpopo, South Africa

Raja Ampat, an archipelago in Indonesia

Detail of an ostrich fern in spring, Washington state

Reynisdrangar (basalt rock formations) on Reynisfjara Beach, Iceland

The Jefferson Memorial during the National Cherry Blossom Festival in Washington, DC

Mountain hare running across snow-covered upland, Scotland

Cradle Mountain-Lake St. Clair National Park, Tasmania, Australia

Ancient Roman gold mining site of Las Médulas, León province, Spain

Humpback whale mother pushes her sleeping calf to the surface, Maui, Hawaii

Satellite image of the Mania River in Madagascar

Tuskegee Airmen reading a map

Bluebell flowers carpet the Hallerbos forest floor, Flanders, Belgium