Sant'Eulalia Archaeological Area

Tucked beneath the Chiesa di Sant'Eulalia, this underground archaeological site lets you walk actual Roman streets on raised walkways, passing ancient wells, mosaics, and medieval layers that built up over centuries. It's a genuinely surreal experience — you're essentially strolling through Cagliari's buried past while a working church sits right above your head. The on-site treasury museum adds even more depth with artifacts and archives tied to the church's long history.