Monte Testaccio
It is thought that Monte Testaccio, the giant mound of broken amphorae that lay behind the Horrea Galbae, was associated with the complex. Olive oil imported from far-away Baetica (in modern Spain) was emptied into bulk containers, probably in the horrea, and the original import vessels were smashed and dumped on Monte Testaccio. The scale of the imports can be judged by the fact that Monte Testaccio is estimated to contain the remains of at least 53 million olive oil amphorae, in which some 6 billion litres (1.58 billion gallons) of oil were imported.