At number 9 Calle Arenal you'll see the entrance to the historic Palacio Gaviria, which was inaugurated by Queen Elizabeth II in the early fifties with a fairy-tale dance in the "Hall of Mirrors". At the time it was one of the most luxurious palaces in Madrid and belonged to a banker from Seville who was one of the ten richest men in Spain. The festivities took place in the magnificent frescoed halls and were "spied on" by the "uninvited" through the balcony windows overlooking Calle Arenal. Until recently, you could rock out at dances in this artistic setting: in fact, for a time the noble mansion was turned into a disco, which has since been closed. There have been various proposals about what to do with this illustrious palace - it once even hosted a traditional Christmas market - but for the moment, it remains closed to the public.