There are only three synagogues surviving from the Sephardic era in Spain, in each case I think they survived by being converted into churches. The synagogue of Cordoba is small and square but very tall, presumably to collect light from above the rooftops. The walls were once covered with white Mudejar style decoration with Hebrew inscriptions and a lot of this survives. In fact there is only one problem with this synagogue. It was obviously only designed to accomodate about 20 or 30 people at a time and the tour groups queue up all the way down the street and wait for a turn to squeeze in. In other words, to really appreciate this monument you have to arrive before they do.