This fascinating museum is also a working salt mine. Its 1001m-deep artesian salt well was the world’s deepest well when it was built in 1835 and it remains the deepest salt well ever made using percussion drilling, a technique invented here and later applied throughout the world.
Many pieces of original equipment, including a 20m-high wooden derrick that towers above the tiny, 20cm-wide mouth of the well, are still intact. On the 2nd floor of the salt house, rows of cauldrons bubble away day and night over fires powered by natural gas, the mine's other product, until only fluffy white piles of glistening salt remain.
There are excellent English captions explaining the process, from how bamboo was once used to siphon brine from beneath the earth to how soy milk is added to clarify it. Bags of the salt (from ¥3.50) are sold from the window to the right when you exit.
Take bus 5 or 35 (¥1, six stops) uphill from the city centre.