A Citroen Aircross concept car is pictured during the media day at the Frankfurt Motor Show (IAA) in Frankfurt, Germany, September 15, 2015. The car show runs through September 27. (Photo by Kai Pfaffenbach/Reuters)

“Not for the faint of heart”. Casa Milà, better known as La Pedrera, is a building designed by the Catalan architect Antoni Gaudí and built during the years 1905–1910, being considered officially completed in 1912. It is located at 92, Passeig de Gràcia in the Eixample district of Barcelona, Catalonia, Spain. (Photo by Stefano Scarselli)

A round circle of smoke coming from the mouth of the Etna volcano is seen in the sky during an eruption on the southern Italian island of Sicily April 11, 2013. Mount Etna is Europe's tallest and most active volcano. (Photo by Antonio Parrinello/Reuters)

Atmosphere at the 84th Annual Hollywood Christmas Parade held at The Roosevelt Hotel on November 29, 2015 in Hollywood, California. (Photo by Zuma Wire/Rex Shutterstock)

Miss Hawaii Allison Chu waves to the crowd as she holds one of her shoes during the 2017 Miss America pageant “Show Us Your Shoes” parade Saturday, September 10, 2016, in Atlantic City. (Photo by Chris Szagola/AP Photo)

Baka pygmies in their forest home preparing food in, Sangha Forest, Central African Republic, February 2016. Here, in their forest home, traditional life continues in the face of multiplying challenges ranging from poachers, to ill health. Deep in the rainforests of central Africa lives one of the world’s most mysterious tribes. (Photo by Susan Schulman/Barcroft Images)

Model Kendall Jenner attends the “120 Battements Par Minutes (120 Beats Per Minute)” screening during the 70th annual Cannes Film Festival at Palais des Festivals on May 20, 2017 in Cannes, France. (Photo by Eric Gaillard/Reuters)

A member of the Air Force's Wings of Blue Parachute Demonstration Team salutes as he jumps out of an aircraft, during the opening ceremony of Aviation Nation 2017 Nellis Air and Space Expo at Nellis Air Force Base, Nev., November 10, 2017. (Photo by Senior Airman Kevin Tanenbaum/Reuters/U.S. Air Force)