We visited the Alhambra in Granada in 1978 or thereabouts. It was breathtakingly beautiful and we were the only people there , other than a couple of handymen/gardeners who were more than happy to show us round.
We went again in 2008 and the place was heaving. We queued from 8am until 11:30 by which time the queue had hardly moved at all. SO...if you want to see it (and it is stunning) make sure you book an organised tour. It was so frustrating to watch coachloads of people being waved in as we continued to wait in line. In the end we gave up and just looked at the gardens ...they too are just stunning.
I am pretty sure I will go back and try again, but I'll book a tour next time.