In a diamond town in the Namibian desert, with no fresh water source of its own, keeping meat fresh was a serious problem.

Kolmanskop’s butcher shop solved it by sharing a wall with the ice factory. Salt water, chilled with ammonia or carbon dioxide next door, was piped through that wall into the cooling room, where electric fans circulated the cold air. A hole let some of it drift into the sales room, which was surely a fine reason to linger at the counter. The original installation is still there.

VoiceMap’s self-guided audio tour of Kolmanskop uses the butcher shop and its neighbour to explain how salt water, which freezes at a lower temperature than fresh, turned fresh water into ice in about 24 hours, and why the shops on Shopping Street were built side by side.