A house built on a rock on the river Drina is seen near the western Serbian town of Bajina Basta, about 160km (99 miles) from the capital Belgrade May 22, 2013. The house was built in 1968 by a group of young men who decided that the rock on the river was an ideal place for a tiny shelter, according to the house's co-owner, who was among those involved in its construction. (Photo by Marko Djurica/Reuters)

The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)

In this Friday, December 5, 2014 photo, Iranian volunteer Asal Moghaddam plays with dogs at the Vafa Animal Shelter in the city of Hashtgerd 43 miles (73 kilometers) west of the capital Tehran, Iran. More than 500 dogs find care and affection at the Vafa Animal Shelter, which was established through an endowment in 2004 and is the country’s only licensed animal refuge. (Photo by Vahid Salemi/AP Photo)

In this photograph taken on June 28, 2015, a hiker in Hong Kong takes a picture of the city from a walking trail. The southern Chinese territory is crisscrossed by more than 180 miles of designated hiking trails. (Photo by Alex Ogle/AFP Photo)

An Afghan girl makes a pile of unbaked bricks near the road passing through the Shamali Plains, about 10 kilometers (6 miles), west of Bagram, Afghanistan, Wednesay April 9, 2003. Children assist parents in their job to supplement family income. (Photo by Gurinder Osan/AP Photo)

A white Bengal tiger cub plays with its mother in a zoo in the Siberian city of Novosibirsk, about 2,800 kilometers (1,750 miles) east of Moscow, Russia, Tuesday, April 21, 2015. Two blue-eyed Bengal tiger cubs were born in March to a couple of white tigers at Novosibirsk zoo. (Photo by Ilnar Salakhiev/AP Photo)

The Öresund or Øresund Bridge is a double-track railway and dual carriageway bridge-tunnel across the Øresund strait between Scania (southernmost Sweden) and Denmark. The bridge runs nearly 8 km (5 miles) from the Swedish coast to the artificial island of Peberholm, which lies in the middle of the strait. The remainder of the link is by a 4 km (2.5 mile) tunnel from Peberholm to the Danish island of Amager. The Øresund Bridge is the longest combined road and rail bridge in Europe, and connects two major metropolitan areas: Copenhagen, the Danish capital city, and the major Swedish city of Malmö. It connects the road and rail networks of Scandinavia with those of Central and Western Europe.

A boy shoots a World War II machine gun armed with blanks at an weapon exhibition during a military show near Kirovsk, about 30 kilometers (19 miles) east of St. Petersburg, Russia, Sunday, January 21, 2018. (Photo by Dmitri Lovetsky/AP Photo)