In this November 2, 2017 photo, Mathew Fulkerson and his wife Leigh Ann pose at their Subterra Airbnb located in a former underground missile silo base near Eskridge, Kan. It was designed to house a nuclear warhead six decades ago – but now, this Cold War silo is the perfect spot for a mini break at just $133 a night. (Photo by Thad Allton/The Topeka Capital-Journal via AP Photo)

A military band prepares to play the national anthems before Cuban President Raul Castro welcomes U.S. President Barack Obama at the Palacio de la Revolucion in Havana March 21, 2016. Barack Obama on Sunday became the first US president in 88 years to visit Cuba, touching down in Havana for a landmark trip aimed at ending decades of Cold War animosity. (Photo by Jonathan Ernst/Reuters)

People use snowshoes during a tour of the Great Kemeri Bog, Latvia, October 17, 2015. The Kemeri bog is more than 8,000 years old and is one of the largest dry moss swamps in the Baltics. A more than decade-long joint restoration of the bog by the European Union and the Latvian government helped the bog recover its high moss marshes, damp black alder forests, floodplain meadows and seaside lakes – features now considered rare in Europe due to industrialisation. (Photo by Ints Kalnins/Reuters)

Deadwood is pictured in the onetime spa and resort town Epecuen, November 5, 2015. Over the past few years the town of Epecuen, located 550 km (341 miles) southwest of Buenos Aires, has been attracting tourists with its eerie apocalyptic atmosphere after a flood submerged it in salt water for more than two decades. Photo by Enrique Marcarian/Reuters)

Natalia Arango works with her mine detector in a zone of landmines planted by rebels groups near Sonson in Antioquia province, November 19, 2015. Women's work takes on a nontraditional meaning for fifteen Colombian women who work to rid the Antioquia Mountains of deadly landmines as the country edges closer to a peace agreement with Marxist rebels to end over a decade of conflict which has claimed 220,000 lives. (Photo by Fredy Builes/Reuters)

Inmates sleep on the steps of a ladder inside the Quezon City jail at night in Manila in this picture taken on July 21, 2016. There are 3,800 inmates at the jail, which was built six decades ago to house 800, and they engage in a relentless contest for space. Men take turns to sleep on the cracked cement floor of an open-air basketball court, the steps of staircases, underneath beds and hammocks made out of old blankets. (Photo by Noel Celis/AFP Photo)

Bulgarian Muslims Azim Liumankov and his bride Fikrie Bindzheva pose in front of their house during their wedding ceremony in the village of Ribnovo, in the Rhodope Mountains, February 15, 2015. The remote mountain village of Ribnovo in southwest Bulgaria has kept its traditional winter marriage ceremony alive despite decades of Communist persecution, followed by poverty that forced many men to seek work abroad. (Photo by Stoyan Nenov/Reuters)