A young man, who says he is part of a local criminal gang, poses for a picture holding a gun in the neighbourhood of Korogcho in Nairobi, Kenya, March 19, 2015. Around 2 million people live in the shantytowns packed in around Kenya's capital. Crime is high amid chronic unemployment levels, while basic services and sanitation are scarce. Residents try to make the best of things, eking out a living and picking up work where they can. (Photo by Siegfried Modola/Reuters)

A woman is supported by two men while crossing a river, north of Idomeni, Greece, as migrants attempt to reach Macedonia on a route that would bypass the border fence, Monday, March 14, 2016. Hundreds of migrants and refugees walked out of an overcrowded camp on the Greek-Macedonian border Monday, determined to use a dangerous crossing to head north. (Photo by Vadim Ghirda/AP Photo)

All throughout history of mankind people were fascinated by time, its flow, and how to measure it. Thus, the science of horology can into being, as people invented more and more sophisticated ways of measuring the passage of time. Truly, it’s one of the most profound characteristics of being a human, to feel and to ponder the meaning of time, its properties, and will we ever be able to move through it, not with it. Now, however, horology is mainly referred to the art of mechanical watchmaking. (Photo by MB&F)

A man carries a block of ice left behind by a hailstorm in Sao Paulo, Brazil, on May 19, 2014. After the severe overnight hailstorm a layer of hailstones as deep as 20 centimeters covered streets and parks, drawing people to make snowmen and play in the ice, an unusual scene to the city. (Photo by Nelson Antoine/AP Photo)

In the build-up to Halloween those hunting for a real-life ghost town need look no further than this haunting spot. Bodie, California, USA – which requires special access to photograph at night – is one of the best preserved ghost towns in America, still featuring the abodes of the former miners who inhabited it more than 100 years ago. Here: Bodie, California, a real-life ghost town. (Photo by Matthew Christopher/Caters News Agency)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

The International Garden Photographer of the Year is one of the world’s premier competitions specialising in botanical photography. There are 11 main categories and numerous special awards including Young Garden Photographer of the Year, and the mobile-only category Gardens on the Go. Here: Winner, Wildflower Landscapes category. Alto Paraíso de Goiás, Goiás, Brazil. (Photo by Marcio Cabral/The Guardian)

A Palestinian woman scuffles with Israeli troops as they demolish sheds belonging to Palestinians near the West Bank village of Yatta, south of Hebron June 19, 2016. (Photo by Mussa Qawasma/Reuters)