Hashima Island, Nagasaki Prefecture, Japan

Hashima Island (端島, or correctly Hashima, as -shima is Japanese for island), commonly called Gunkanjima or Gunkanshima (軍艦島; meaning Battleship Island), is one among 505 uninhabited islands in the Nagasaki Prefecture about 15 kilometers from Nagasaki itself.
The island was populated from 1887 to 1974 as a coal mining facility. The island's most notable features are the abandoned concrete buildings and the sea wall surrounding it. It has been administered as part of Nagasaki city since 2005; it had previously been administered by the former town of Takashima.
It is known for its coal mines and their operation during the industrialization of Japan. Mitsubishi bought the island in 1890 and began the project, the aim of which was retrieving coal from undersea mines. They built Japan's first large concrete building (9 stories high), a block of apartments in 1916 to accommodate their burgeoning ranks of workers (many of whom were forcibly recruited labourers from other parts of Asia) and to protect against typhoon destruction. According to a South Korean commission, the island housed 500 Koreans who were forced to work between 1939 and 1945, during World War II.
In 1959, the 15-acre island's population reached its peak of 5,259, with a population density of 835 people per hectare (83,500 people/km2, 216,264 people per square mile) for the whole island, or 1,391 per hectare (139,100 people/km2) for the residential district.