Men rest after salvaging metal on the 30th floor of the “Tower of David” skyscraper in Caracas February 3, 2014. A 45-storey skyscraper in the center of Venezuela's capital Caracas is a slum, probably the highest in the world. Dubbed the “Tower of David”, the building was intended to be a shining new financial center but was abandoned around 1994 after the death of its developer – banker and horse-breeder David Brillembourg – and the collapse of the financial sector. (Photo by Jorge Silva/Reuters)

Model, skydiver and wing-suit jumper Roberta Mancino, 33, swims with a whale shark on February 2014 in Isla Mujeres, Mexico. A female skydiver swims with whale sharks, manta rays and sailfish – the fastest fish in the sea. Model, skydiver and wing-suit jumper Roberta Mancino, 33, jumped from a boat into the ocean surrounding Isla Mujeres near the northern Peninsula of Mexico. The incredible project involved two trips to the stormy winter seas – one in February 2013 and one a year later in February 2014. (Photo by Shawn Heinrichs/Barcroft Media)

A passenger waits after his train arrived in Nouadhibou, Mauritania’s second largest city and the main export port for the country’s iron ore industry, on June 25, 2014. The mining company’s employees proudly call their firm the lung of their nation's economy and the train that ferries the ore to the coast stretches some two kilometres, making it one of the world's longest. SNIM mines black iron ore in the northern town of Zouerate, a remote desert location which nevertheless attracts people from all over the country looking for work. (Photo by Joe Penney/Reuters)

A person drags a suitcase as a boy clings to it on a square in front of a railway station ahead of the Chinese Lunar New Year in Qingdao, Shandong province, January 28, 2014. About 3.62 billion trips will be made during the 40-day Spring Festival travel rush, which started from January 16, reported Xinhua News Agency citing a government official. (Photo by Reuters/China Daily)

Spanish runner Francisco Contreras, 77, known as “Super Paco”, runs as he participates in the XVIII 101km international competition in the outskirts of Ronda, southern Spain, May 9, 2015. About 7,000 participants, including runners, mountain bikers and duathletes, run a track of 101 km (63 miles) in less than 24 hours through the “Serrania de Ronda” (Ronda Mountain Range) during this competition organised by the 4th Tercio (Regiment) “Alejandro Farnesio” of the Spanish Legion. The Puente Nuevo is 120 metres (394 feet) high over the gorge of the river that divides the city of Ronda. Picture taken using long exposure. (Photo by Jon Nazca/Reuters)

A Nepalese woman sits inside her house in an alley of Bhaktapur, 12 kilometers (7.5 miles) east of Kathmandu, Monday, May 25, 2015, one month after the deadly 7.8 magnitude earthquake hit Nepal. Two powerful earthquakes devastated Nepal on April 25 and May 12, killing nearly 8,700 people and injuring 16,800 others. The quakes and aftershocks also triggered many landslides in the Himalayan nation, which boasts eight of the world's highest mountains gets about half a million tourists every year, with many coming to trek the Himalayan nation's scenic mountain trails. (Photo by Niranjan Shrestha/AP Photo)

An Iraqi special forces soldier wears a rose in his body armor as troops move from the Yarmouk neighborhood to take another district from Islamic State militant control in Mosul, Iraq, Wednesday, April 12, 2017. (Photo by Maya Alleruzzo/AP Photo)

In this Monday, June 5, 2017, file photo, an Indian woman walks as se searches for recyclable materials at a garbage dumping site on the outskirts of Gauhati, Assam state, India. (Photo by Anupam Nath/AP Photo)