Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

Participants compete in the Mud Day Race extreme run competition at El Goloso military base, outside Madrid, Spain, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (Photo by Juan Medina/Reuters)

In this Saturday, April 8, 2017 photo, a keeper walks camels to the Al Marmoom Camel Racetrack, in al-Lisaili about 40 km (25 miles) southeast of Dubai, United Arab Emirates. Camel racing is a big-money sport and fast thoroughbreds can fetch well over a million dollars. As rising temperatures across Gulf Arab countries signal the end of the winter camel racing season, Dubai is wrapping up its races with the annual Al Marmoom Heritage Festival that has drawn thousands of camels from across the oil-rich Gulf. (Photo by Kamran Jebreili/AP Photo)

A member of Team Chez Victor falls in the water while competing during the Ice Canoe race at the Quebec Winter Carnival in Quebec City, February 5, 2017. (Photo by Mathieu Belanger/Reuters)

An extraordinary work of art has just been completed in Scotland. The Kelpies by figurative sculptor Andy Scott surge upwards in steel, whinnying and snorting alongside the banks of the Forth and Clyde Canal near the town of Falkirk. These fantastic beasts from Gaelic mythology have risen again as monuments to the horse-powered industrial heritage of Scotland.

Riders negotiate a dune as they compete in the Adult Solo race at the HydroGarden Weston Beach Race in Weston- super- Mare, south west England, on October 9, 2016. Beach racing is an offshoot of enduro and motocross racing. Riders on solo motorcycles and quad bikes compete on a course marked out on a beach, with man- made jumps and sand dunes being constructed to make the course tougher. (Photo by Adrian Dennis/AFP Photo)

A competitor loses his shoe during the annual race on high heels during Gay Pride celebrations in the quarter of Chueca in Madrid, Spain, June 30, 2016. (Photo by Susana Vera/Reuters)

Farmer Franz Schaller rides on an ox called Napoleon during a traditional ox race in the southern Bavarian village of Muensing near Lake Starnberg, Germany August 28, 2016. (Photo by Michaela Rehle/Reuters)