Huesca

Loarre
One of the best Romanesque castles in Europe recently the site for Ridley Scott's film, Kingdom of Heaven just has a one-man bar hidden behind a few rocks, and a part-time guide. Close to Huesca city.

Although you might be attracted to the high Pyrenees, you should definitely visit the pre-Pyrenees - a parallel range just to the North of Huesca city.

The Sierra de Guara for mountaineering and birdwatching vultures and birds of prey.

Ordesa National Park
is particularly spectacular in autumn. In summer some of the waterfalls dry up. No cars.
Barbastro
Small town with an interesting old part, centre of the Somontano wine district. You can visit vineyards from here.
Ainsa
Ansó and Alquézar are beautiful, well preserved Romanesque villages in mountainous regions. There are other, less well-known places which are also charming.
San Juan de la Peña
has to be seen - part Romanesque, part Gothic shrine set into an enormous rock in lovely mountain scenery. Easily accessible from Huesca.
Jaca
has an important Romanesque cathedral and fortifications reputed to be designed by Leonardo de Vinci they're not.
Villanueva de Sigena
The Monastery of Santa María de Sigena is located next to the town. Birthplace of Michael Servetus, the discoverer of pulmonary circulation with a museum dedicated to his work.