The Øresund Bridge that connects Sweden to Denmark and dives into the sea

The Øresund strait separates Sweden from Denmark, and the bridge linking the two nations is a masterpiece of engineering and architecture that has few equals in the world. The two connected cities are Copenhagen, the Danish capital city, and the Swedish city of Malmö. The bridge, the longest combined road and rail bridge in Europe, runs nearly 8 kilometres from the Swedish coast to the artificial island Peberholm in the middle of the strait. The crossing is completed by the 4-kilometre Drogden Tunnel from Peberholm to the Danish island of Amager.
The highway for motor vehicles is located at the upper level of the bridge, while the railway line is located at the bottom. Inside the tunnel, the various roadways flank each other and run parallel under the sea, together with the emergency tunnels provided inside the tunnel.

The artificial island that connects the bridge and the tunnel, called Peberholm, has undergone an unexpectedly positive impact on local flora and fauna. All animals were allowed to develop the new habitat freely, and the island has become a privileged place for biologists to observe birds and the rare green toad.

The responsibility for the maintenance of the bridge is divided between the two countries, and the decidedly high tolls allow the structure to be kept fully operational.
Digging a tunnel for part of the way, rather than raising that section of the bridge, had a purpose to avoid interfering with air traffic from the nearby Copenhagen Airport. Construction began in 1995, with the bridge opening to traffic on 1 July 2000.
DKK 30.1 billion (about €4.0 billion) was needed to build the bridge, but its completion allows over 3.5 million people to move from one state to another as united by a natural isthmus, and shortens the distances between two peoples divided from the sea but united by an architectural masterpiece.

Source and Images: wikipedia