The hills and coastline of Quartu Sant'Elena are home to 38 Nuragic settlements, the most beautiful of which is the Nuraghe Diana, dating from the middle of the 2nd millennium BC between the Late Bronze and Early Iron Ages and built to guard the Nuragic port. The Nuraghe Diana complex is unique, as the wall enclosing the inner courtyard was designed and built at the same time as the tower toppoed with a tholos false dome and the other two smaller connected towers. This modus operandi makes it unique among nuraghi that were expanded over time and only later were the other buildings annexed to the central tower. The construction technique is also an enigma, revealing unusual architectural and stylistic skills, a quest for beauty and a challenge to the laws of physics.