Your visit to the archaeological site of Nora (near Pula) can be completed with a visit to the Tower of Coltellazzo, a Spanish construction placed on top of a volcanic promontory. The Tower, built by Philip II between 1580 and 1610, was part of a defensive system set up by the Spanish to defend their territories from the incursions of the African Berbers.
Today, the monument hosts a lighthouse. Although it cannot be visited inside, the climbing up to its entrance makes all your efforts worthwhile: the view from that point embraces on one side the Gulf of Cagliari and on the other the ruins of Nora and the hills of Santa Margherita. An easy walk for a later afternoon.