It literally is a mountain made of salt - a weird geological feature that made the local duke one of the richest people in medieval Spain. For a truly different experience you can go on a tour of the mine workings. Walking down white crystalline tunnels deep underground and coming across colourful shrines left by superstitious miners from years gone by is both surreal and strangely touching. There is some information in English but not all the guides speak it so check beforehand. The local village, Cardona, is dominated by a 9th Century castle that has been converted into a Parador - a classy, state-owned hotel. It's pricey but immaculate with top-notch food and views to die for. If you don't want to stay you can have a look round the battlements for free so you can take some photos of the view.
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