Step back several centuries as you head into medieval Castello, the old walled city perched atop a steep hill. Walk up the Via dell’Università to the first of Cagliari’s watchtowers, Torre dell’Elefante, built in 1307. (The second, Torre di San Pancrazio, is on higher ground to the north.) Be sure to take note of the little stone elephant carved into one side. The 30-meter tower guarded the western entrance to Castello, and visitors can climb its four floors (past former storehouses, an armory and a prison).