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)

Members of the public interact with “Impulse” by Lateral O ce and CS Design during Lumiere London festival of light 2018 on January 18, 2018 in London, England. Lumiere London is a four night long light festival spanning the British capital with more than 50 artworks by UK and international aritsts. (Photo by Dan Kitwood/Getty Images)

A dark Devon Rex cat is held by its owner during a competition in Bucharest, Romania, Saturday, September 26, 2015. More than 300 cats entered the international feline beauty competition in the Romanian capital. (Photo by Vadim Ghirda/AP Photo)

Ethiopian Airlines female pilots prepare the plane before takeoff at Bole international airport in the capital Addis Ababa, November 19, 2015. Ethiopia Airlines on Thursday, dispatched its first ever all-female operated flight. Every aspect of the journey was handled by women, from the ground crew, aircraft maintenance to traffic controllers. Gualu and her co-pilot were charged with flying the crew and passengers to Bangkok, Thailand. (Photo by Tiksa Negeri/Reuters)

Two life-size Victorian style dolls shocked Londoners morning December 3, 2015 as the creepy pair popped up at commuter hotspots across the capital to mark the launch of the world's first psychological theme park ride created by Derren Brown, coming to Thorpe Park Resort in 2016. (Photo by Matt Alexander/PA Wire)

A police officer detains a woman on suspicion of collaborating with the 18th street gang during a "Safe House" operation at the Concepcion neighbourhood in San Salvador, July 2, 2015. Salvadoran police make “Safe House” operations at dangerous neighbourhoods of the capital to prevent murders, according to local media. (Photo by Jose Cabezas/Reuters)

People stroll alongside one of the hills of the Tio Pio park in Madrid, Monday, January 25, 2016. The park is a high viewpoint frequented mostly by locals due to its view of the Spanish capital skyline. (Photo by Francisco Seco/AP Photo)

A Sphynx cat stares sitting on its owner's lap during an international feline beauty competition in Bucharest, Romania, Saturday, April 14, 2018. More than 250 cats take part in the two-day competition in the Romanian capital. (Photo by Vadim Ghirda/AP Photo)