Girona's medieval city walls survive in remarkable condition and have been turned into a walkable promenade — the Passeig Arqueològic — that runs along the eastern edge of the old city. Walking the walls gives the best elevated views over the cathedral, the old town roofscape, and the Pyrenean foothills beyond.
The walk takes about 30 minutes at a leisurely pace. The walls date from Roman times through to the 17th century, with towers from different periods visible along the route. Access points are at various points in the old city; the stretch near the university garden is particularly pleasant. Entry is free.