Segovia, with its Roman aqueduct and its medieval architecture, defintely ranks among the best WHS I've seen so far. Although the aqueduct and the cathedral were wonderful in their own right, the Alcazar was the highlight of my visit. It was a lot bigger than I had imagined with many interesting rooms containing armour, Flemish tapestries and the like. At the time of my visit, there was also an exhibition displaying restored paintings and sculptures that I found quite amusing. The view of the cathedral and the surrounding areas from the top of the tower of Juan II is magnificant (see picture) although the climb up to the top is unpleasant at best (definitely not for the claustrophobic). Segovia is also home to many ancient churches although most were closed on the day we visited (Monday). It is possible to combine a visit to this city with Avila (another WHS) on the same day. It was a little rushed but I managed to see all the sites I wanted.