El Escorial Day-Trip is a real time commitment — fit it in only if it's a priority.
Allow Half to full day.
An overwhelming feat of Habsburg power: the vast monastery, royal pantheon and library are sombre and impressive, set against cool mountain air. The catch is its deliberate austerity can read as cold and monotonous, the visit is long and footsore, and it's the least 'fun' of the three day-trips.