We parked on top of a mountain :)
La Picota - we paid 8 Euros a night to park here. And we stayed for 3 nights. Trust us, we are very cheap people, so this must have been a fantastic place if we were keen to pay for it. Close to the parking was a "mythological" forest and at the end of it the most amazing view of Picos de Europa. Down the other way there were a bunch of beautiful waterfalls.
Indeed one of the best places we parked at.