The Zero Gravity Research Facility at the NASA Glenn Research Center in Cleveland, Ohio is a unique facility designed to perform tests in a reduced gravity environment. The facility uses vertical drop tests in a vacuum chamber to investigate the behavior of components, systems, liquids, gases, and combustion in such circumstances.

The Zero-G facility has been operational since 1966. It was originally designed and built during the space race era of the 1960s to support research and development of space flight components and fluid systems, in a weightless or microgravity environment. 

The facility is currently used by NASA funded researchers from around the world to study the effects of microgravity on physical phenomena such as combustion and fluid physics, to develop and demonstrate new technology for future space missions, and to develop and test experiment hardware designed for flight aboard the International Space Station or future spacecraft.

The facility consists of a concrete-lined shaft, 28 feet (8.5 m) in diameter, that extends 510 feet (160 m) below ground level. A steel vacuum chamber, 20 feet (6.1 m) in diameter and 470 feet (140 m) high, is contained within the concrete shaft. The pressure in this vacuum chamber is reduced to 13.3 pascals (1.3×10−4 atm) before use. Test equipment is typically mounted in a cylindrical container, and has a maximum weight of 2,500 pounds (1,100 kg). Equipment dropped in the chamber experiences microgravity for about 5.15 seconds before landing in a deceleration cart filled with expanded styrofoam beads; it typically experiences 32g during deceleration but may range up to 65g. The service building at the top of the shaft contains a shop area, control room, and a clean room.

According to; Source of photos: internet