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 photograph of Cuba's former President Fidel Castro decorates a wall inside a state-run market in Havana, March 8, 2016. (Photo by Alexandre Meneghini/Reuters)

A man exercises in the early morning on a hilltop overlooking Kabul, Afghanistan March 3, 2016. (Photo by Mohammad Ismail/Reuters)

Schoolchildren play music to entertain and inspire people on their way home from work Tuesday, March 29, 2016 in Pyongyang, North Korea. North Korea has called a 70-day loyalty drive areas of a major congress of the ruling party scheduled for early May and everyone from students to coal miners have been mobilized nationwide to demonstrate their devotion to the leadership. (Photo by Eric Talmadge/AP Photo)

A Lebanese man is reflected in a pool of dirty water as he casts his fishing pole from a rocky coastal area along the Beirut coastline, Lebanon, Monday, October 3, 2016. (Photo by Hassan Ammar/AP Photo)

An undated handout picture made available by the Symbio Wildlife Park on 28 November 2016 shows three Pygmy Marmoset monkeys including an adult male, a female juvenile and a four-week-old baby, at the Symbio Wildlife Park in Helensburgh, South of Sydney, New South Wales, Australia. (Photo by EPA/Symbio Wildlife Park)

In this September 1, 2016 photo, 90-year-old street vendor Antonio Bauza waits for tourists to sell his bananas, next to the village church in Remedios, Cuba. With the arrival of the first commercial flights from the U.S. to Cuba in more than 50 years, the Cuban government is welcoming the wave of new visitors and struggling to update infrastructure that's already overwhelmed. (Photo by Ramon Espinosa/AP Photo)

Tourists pose for a selfie in Cancun, October 13, 2015. Cancun's transformation in the 1970s from a small Caribbean fishing village into a strip of nightclubs and high-rise hotels has reduced biodiversity and polluted water resources as infrastructure struggles to keep up. (Photo by Edgard Garrido/Reuters)