Cagliari’s most significant Roman monument is this 2nd-century amphitheatre. Currently resembling a messy construction site (it's closed for restoration), the structure is carved into the rocky flank of the Buon Cammino hill, near the northern entrance to Il Castello. Over the centuries much of the original theatre has been cannibalised for building material, but enough survives to stir the imagination.
In its heyday, crowds of up to 10,000 people – practically the entire population of Cagliari – would gather in the steeply stacked stands to watch gladiators battle each other and the occasional wild animal.