While hiking this area I spotted, literally, hundreds of boulders ranging from small, sit-start-only rocks to 20ft - 30ft, maybe even 40 ft high boulders on skyline ridges.

The area is cross-crossed with old farming roads and trails.  Minimal bush crashing would be needed to get to the boulders, as can be seen in the photos.  Some may be off limits due to being too close to infrastructure [water pipes from dam(s) ] 

The town itself is tiny, to say it has "limited facilities" would be to over-rate it. (e.g. No groceries, no gas, ) It  does have one good “ hotel-inn” .  ( we stayed at the La Gosta Perdida) but there are one or two others listed. 

 Whether there would be an objection to overnight camping in the Park I have no idea. Do NOT expect the “ National Park” to be anything like those in the USA in terms of development or facilities. ( or crowds !!!...or rescue ! ) 

Located on Portugal’s northern border with Spain.  If you follow the border inland from the coast, the tiny town of Montesinho is located just before the border turns and heads south.  It is about 70 miles ( “ as the crow flys”) Northeast of Chaves and about 20 miles due north of the town of Braganca.  See Map. GPS locator is located in the Town “Square“.