Running from the Puerta del Sol to the Cathedral of La Almudena, it has always been Madrid's main street where, in the Moslem era, the souk was established and where, in the Middle Ages, shops, taverns, gaming houses and lovenests attracted the crowds. In the narrow house at No. 61 lived Pedro Calderon de la Barca, next to the Queen Mother's former pharmacy. The Italian Institute occupies No. 87, an old 17C palace. Opposite stands the former Uceda Palace, from the same period.