Construction has begun on a large, high altitude cosmic-ray observatory in the Ganzi Tibetan Autonomous Prefecture, Sichuan Province, which is expected to become one of the world's four biggest research institutes in the field.

When completed, the observatory will be one of the four biggest cosmic-ray observatories in the world. The other three are located in South America, the South Pole and Europe.

The project, Large High Altitude Air Shower Observatory (LHAASO), was approved by the National Development and Reform Commission in December 2015 with an estimated budget of 1.2 billion yuan ($187.2 million), and is expected to be completed by 2020.

The Water Cherenkov Detector Array (WCDA) pool has a total area of 78,000 cubic meters, including two 150 meters by 150 meters and one 110 meter by 300 meter pool. The horizontal excavation height is about 4397.05 to 4395.5 meters. It is expected that the pool will be completed by the end of June.