Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

Artists perform during the opening show directed by German director Volker Hesse, on the opening day of the Gotthard rail tunnel, at the fairground Rynaecht at the northern portal in Erstfeld, Switzerland, Wednesday, June 1, 2016. The construction of the 57 kilometer long tunnel began in 1999, the breakthrough was in 2010. After the official opening on June 1, the commercial operation will start in December 2016. (Photo by Ruben Sprich\Pool Photo via AP Photo)

Revellers celebrate New Year's Day in central Moscow, Russia, January 1, 2016. (Photo by Tatyana Makeyeva/Reuters)

Internally displaced Syrian children play inside a refugee camp in the Hama countryside, Syria January 1, 2016. (Photo by Ammar Abdullah/Reuters)

Participants take part in a New Year's Jump into the Sea in Portoroz , Slovenia, January 1, 2016. (Photo by Srdjan Zivulovic/Reuters)

A woman walks inside a building in downtown Havana, Cuba April 21, 2016. (Photo by Alexandre Meneghini/Reuters)

A woman shields her face from the sun as she rides her scooter in Ahmedabad, India May 20, 2016. (Photo by Amit Dave/Reuters)

An internally displaced Afghan girl holds a child at a refugee camp in Kabul, Afghanistan May 31, 2016. (Photo by Mohammad Ismail/Reuters)