Ski tunnel
Indoor skiing is done in a climate-controlled environment with snowmaking. This enables skiing and snowboarding to take place regardless of outdoor temperatures. Facilities for both alpine skiing and nordic skiing are available.
Tunnel under construction in Planica, Slovenia will be opened in June 2016.
The first indoor ski slope, "Schneepalast" (German for snow palace) operated from 26th November 1927 to May 1928 in Vienna in an abandoned railway station, the Nordwestbahnhof. The snow was made of soda. The world's first commercial indoor ski slope operated from 1987 to 2005 at Mount Thebarton, in Adelaide, South Australia.
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Wikipedia