Jaca is most often reached from Huesca, the provincial capital, by bus or train. However it provides one of the easiest entrances to Spain over the Pyrenees from Oleron Ste Marie in France and if you have reached the Ordesa National Park from the east, it it is easy to get a bus to Sabananigo and change for Jaca.
The town itself has an interesting cathedral and an extensive citadel but it does lie a short distance away from the mountains which are the main attraction for most visitors. Even so it provides a good centre for a holiday with a car. Those dependent on public transport may prefer to stay further into the mountains.