YES, Tunisia has kasbahs (castles) and medinas (old quarters) aplenty to explore. The Lonely Planet guide suggests walking tours of the old quarters of several cities. Timing matters: those tortuous lanes lose much of their charm when the shutters slam shut.
In the cosmopolitan port of Sousse, two hours from Tunis, the streets of the medina tumble down to the sea front. From the ramparts of an imposing ninth-century ribat or monastic fort, you can peer down into the Great Mosque and gaze out across to the ancient kasbah beyond a sea of white-washed cubes. Down in the laneways lie mosques and mausoleums from Ottoman times, medieval cisterns as well as the ubiquitous souvenir shops and carpet dealers of the covered souqs.