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Mirny Diamond Mine

The Mir mine, also called the Mirny mine, is an open pit diamond mine located in Mirny, Sakha Republic, in the Siberian region of eastern Russia. The mine is >525 meters (1,722 ft) deep (4th in the world) and has a diameter of 1,200 m (3,900 ft), and is one of the largest excavated holes in the world.

Borovsko Bridge

The Borovsko Bridge is an unfinished highway bridge near Borovsko , part of Bernartice municipality, Central Bohemian Region, Czech Republic. It is commonly known as the "Czech Avignon" or "Hitler's Bridge".

Željava Air Base

Situated in the west of Bosnia on the border with Croatia, Objekat 505, as it was officially known, was the largest underground airport in the Balkans. The primary purpose of the Objekat 505 was to house a long-range radar early warning system, akin to NORAD, as well as to provide a strategic command center for the country’s defense.

Vajont Dam

The Vajont Dam (or Vaiont Dam) is a disused dam in Italy, which was completed in 1959. On 9 October 1963, during initial filling, a massive landslide caused a man-made megatsunami in the lake in which 50 million cubic metres of water overtopped the dam in a wave 250 metres (820 ft) high, leading to 1,910 deaths and the complete destruction of several villages and towns.

The Black Hills Ordnance Depot

The complex contains over five hundred nuclear-hardened concrete military bunkers, partially buried underground and protected by thick berms of earth, to resist a surface blast wave, as well as radioactive fallout.

Kola Superdeep Borehole

The Kola Superdeep Borehole was a scientific project undertaken by the Soviet Union in the 1970s to better understand the Earth’s crust.

Bagger 288

Bagger 288 (Excavator 288), built by the German company Krupp for the energy and mining firm Rheinbraun, is a bucket-wheel excavator or mobile strip mining machine.

Stelling van Amsterdam

The Stelling van Amsterdam was the most advanced military structure of its type in the world - 135 km (84 miles) of forts, batteries and moats completely encircling the city in a defensive barrier.

The Norias of Hama

The norias of the ancient Syrian city of Hama are seventeen historic waterwheels located along the Orontes River that date back to the Byzantine Era.

The Kauri Driving Dams

Some 3,000 driving dams once existed throughout New Zealand, with the last built during the late 1930s. As the timber industry dwindled, gradually the dams decayed and disappeared and now only a few remain as relics of this destructive industry.

The Outer Trial Bank

The Outer Trial Bank is a circular artificial island in the Wash, East Anglia, England. It is one of two islands constructed during the 1970s for a governmental water resources scheme.

The Unfinished Obelisk

The unfinished obelisk is the largest known ancient obelisk and is located in the northern region of the stone quarries of ancient Egypt.

Vozrozhdeniya Island

In 1948, a top-secret biological weapons laboratory, nicknamed Aralsk-7, was established here. Until its closure in the 1990s, the laboratory tested some of the deadliest pathogens known to man, including plague, anthrax, smallpox, brucellosis, tularemia, botulinum and Venezuelan equine encephalitis.

The Soledar Salt Mines

Some 250 million years ago, a part of Ukraine was under a shallow ocean. When the ocean dried up, it left behind a huge deposit of salt.

Project Riese

Riese is the code name for a construction project of Nazi Germany in 1943–1945, consisting of seven underground structures located in the Owl Mountains and Ksiaz Castle.

The Kelvedon Hatch: Secret Nuclear Bunker

The Kelvedon Hatch Secret Nuclear Bunker at Kelvedon Hatch, in the Borough of Brentwood in the English county of Essex, is a large underground bunker maintained during the cold war as a potential regional government headquarters.

Excelsior Tunnel

In 1959 it was the centre of project Military Atomic Energy Authority operation orpheus investigating the possibility of masking the seismic signal given out by underground nuclear tests.