Probably the most noticeable monument in Cagliari. It was built in white limestone at the end of the 19th century, after Cagliari ceased to be a military fortress and gradually its defensive walls were pulled down. It is the result of three fortified bastions which were then joined together. From piazza Costituzione, the first thing you see is a mighty double staircase surmounted by a large arch. Once you reach the top, you are met by a vast terrace with benches and palm trees. The view is breath-taking. You don't have to walk up all the steps and the lazy visitor can take the lift (open 24/7, free of charge), which is about 100m further up along viale Regina Elena. Don't miss the romantic sunset, before you walk down to the Marina quarter for dinner. 

Admission free.