BOOK THIS HOTEL
We loved Santillana del Mar, and the Casa Del Marqués is a really significant and important part of it. It's pedestrianised apart from the vehicles of a few locals who still live (and farm!) in the old village. We would have liked to see the cave paintings in Cuevas de Altamira but visitor numbers are restricted for preservation reasons, so you have to book months in advance. The rest of the cave is open as normal though.