Going down deep to test travelling into the heights: In the 200-metre-deep shaft of an underground limestone quarry near Helsinki, a company is experimenting with new lifts for skyscrapers. | Image: Getty Images/Bloomberg/Roni Rekomaa.

Edutainment in an abandoned salt mine: The city of Turda in Romania boasts a mining museum with spectacular lighting. | Image: Getty Images/Luxy Images.

Shielded from the light of day: Under a kilometre-thick layer of rock in an old zinc mine in Kamioka in Japan, 13,000 detectors are looking for rare neutrinos. | Image: Andreas Gursky/Pro Litteris, Bonn 2018, Courtesy Sprüth Magers.

The government bunker in Utzigen was built in the 1980s and was intended to house the cantonal government of Bern in times of war. | Image: Valérie Chételat.

A homage to the colliery: Andreas Gursky’s installation of mineworkers’ clothing and equipment, which they used to hang up to dry in the ‘Bergwerk Ost’ colliery in Hamm (Germany), now abandoned. | Image: Andreas Gursky/Pro Litteris, Bonn 2018, Courtesy Sprüth Magers.