A new video from Tom Scott takes viewers inside Deepstore, an archive located about 150 meters underground and a kilometer into a working salt mine near Winsford, England. The mine retains large salt pillars to maintain a stable roof and create rooms. The salt keeps the atmosphere naturally dry, and racks prevent any direct contact between salt and the stored artifacts. While most of the contents of the mine are private, Deepstore is known to hold files from the British National Archives and core samples from soil tests for the Crossrail railway construction in London.