Barbados HARP Gun

The Barbados HARP Gun, was part of Project HARP, short for High Altitude Research Project, which was a joint project of the United States Department of Defense and Canada’s Department of National Defence created with the goal of studying ballistics of re-entry vehicles at low cost; whereas most such projects used expensive and failure-prone rockets, HARP used a non-rocket spacelaunch method based on a very large gun to fire the models to high altitudes and speeds.

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.