Battle-weary American troops withdraw from Yong San in Korea. (Photo by Keystone/Getty Images). 1950

Neapolitan Christmas Nativity figurines on display at “Maestri Ferrigno”, which opened in 1836, at Via San Gregorio Armeno on December 14, 2011 in Naples, Italy. Via San Gregorio Armeno, Christmas Alley as it is known, is considered by many to be the world capital of the Nativity and home to the artisans and merchants who specialize in the art and the craft of the Neapolitan Presepe. Over the Christmas period, more than half a million tourists come to see the shops. (Photo by Franco Origlia/Getty Images)

A surfer rides a wave at the snowy beach of Unstad, in Lofoten Island, Arctic Circle, on March 9, 2016. Surfers from all over the world comes to Lofoten island to surf in extrem conditions. Ocean temperature is 6-7 °C, air temperature around 0°C in spite of a weather very unstable. (Photo by Olivier Morin/AFP Photo)

Jassen Todorov, 40, from San Francisco is a professor of music at San Francisco State University, but he took to helicoptering in his spare time. While he was content to keep the panoramic views he witnessed to himself, Todorov has now paired his passion for flying with photography to capture some of the United States’ undiscovered vistas. Here: Grand Prismatic Spring, Yellowstone, Wyoming. (Photo by Jassen Todorov/Caters News)

A man rides a horse through a bonfire as part of a ritual in honor of Saint Anthony the Abbot, the patron saint of domestic animals, in San Bartolome de Pinares, Spain, Saturday, January 16, 2016. On the eve of Saint Anthony's Day, dozens ride their horses through the narrow cobblestone streets of the small village of San Bartolome during the “Luminarias”, a tradition that dates back 500 years and is meant to purify the animals with the smoke of the bonfires and protect them for the year to come. (Photo by Francisco Seco/AP Photo)

Revellers continue to party and dance through the night and day during the second day of the San Fermin Running Of The Bulls festival, on July 7, 2014 in Pamplona, Spain. The annual Fiesta de San Fermin, made famous by the 1926 novel of US writer Ernest Hemmingway “The Sun Also Rises”, involves the running of the bulls through the historic heart of Pamplona. (Photo by Christopher Furlong/Getty Images)

A fairy tale and movie-themed gingerbread house creation, featuring a reindeer, made by pastry students of the San Ysidro Adult School Culinary Arts program is pictured during their 9th annual gingerbread house competition in San Ysidro, California December 9, 2014. The students' voting results will be delivered back to their class but the official judging will be performed by chefs and culinary experts during the 9th annual event. (Photo by Mike Blake/Reuters)

A man stands beside the Philippine flag as colorful umbrellas adorn a village hall in suburban San Juan, east of Manila, Philippines, on June 27, 2013. (Photo by Aaron Favila/Associated Press)