Monte Testaccio is a hundred-foot high, kilometre-round pile of broken potsherds. The great mound of ceramic refuse, started in the first century BCE, was added to daily over the following four centuries. Co-existent with the Roman Empire, it grew into a mass whose sheer bulk and consistency could not be reduced. Unlike the empire, it did not fall. Pottery is an especially obdurate artefact, but every single piece of pottery in Monte Testaccio is of a particular sort: each fragment is a sherd of broken oil amphora.