KAGRA (or Kamioka Gravitational Wave Detector, formerly called the Large Scale Cryogenic Gravitational Wave Telescope or LCGT) is a pair of gravitational wave interferometers under construction in a mine in Japan. They use cryogenic mirrors to help reduce noise, specifically mirrors made of sapphire, which, along with their suspension mounting, will be at 20 K during operation. They aim for a sensitivity capable of detecting two to three events a year.
Tunnel excavation was complete in 2014 and construction has progressed. Full operation at its target sensitivity is expected in 2018 or 2019.