It is one of the largest spoil heaps found anywhere in the ancient world, covering an area of 2 hectares (4.9 acres) at its base and with a volume of approximately 580,000 cubic metres (760,000 cu yd), containing the remains of an estimated 53 million amphorae.

[2][3] It stands a short distance away from the east bank of the River Tiber, near the Horrea Galbae where the state-controlled reserve of olive oil was stored in the late 2nd century AD.

The huge numbers of broken amphorae at Monte Testaccio illustrate the enormous demand for oil of imperial Rome, which was at the time the world's largest city with a population of at least one million people.

[5] Studies of the hill's composition suggest that Rome's imports of olive oil reached a peak towards the end of the 2nd century AD, when as many as 130,000 amphorae were being deposited on the site each year.

[6] Monte Testaccio was not simply a haphazard waste dump; it was a highly organised and carefully engineered creation, presumably managed by a state administrative authority.

Excavations carried out in 1991 showed that the mound had been raised as a series of level terraces with retaining walls made of nearly intact amphorae filled with sherds to anchor them in place.

[7] Indeed, some of the inscriptions found on mid-2nd century vessels at Monte Testaccio specifically record that the oil they once contained was delivered to the praefectus annonae, the official in charge of the state-run food distribution service.

[3][4] The tituli picti on the Monte Testaccio amphorae tend to follow a standard pattern and indicate a rigorous system of inspection to control trade and deter fraud.

Apart from single names, many inscriptions list combinations such as "the two Aurelii Heraclae, father and son", "the Fadii", "Cutius Celsianus and Fabius Galaticus", "the two Junii, Melissus and Melissa", "the partners Hyacinthus, Isidore and Pollio", "L. Marius Phoebus and the Vibii, Viator and Retitutus."

As Peña notes, directing these vessels "toward state-sponsored construction projects for use as space-fillers in concrete vaulting, the praefectura annonae could have succeeded in disposing of substantial numbers of highly cumbersome and otherwise useless oil containers, while at the same time reducing the amount of lime, sand and rubble that would have been required to complete these initiatives.

[14] A 19th-century traveller, visiting a few years earlier, described the annual festival that was held on the summit of the hill: Each Sunday and Thursday during the month of October, almost the whole population of Rome, rich and poor, throng to this spot, where innumerable tables are covered with refreshments, and the wine is drawn cool from the vaults.

Gay groups dancing the saltarella, intermingled with the jovial circles which surround the tables; the immense crowd of walkers who, leaving their carriages below, stroll about to enjoy the festive scene ...[15]The hill gained a brief military significance in 1849 when it was used as the site of an Italian gun battery, under the command of Giuseppe Garibaldi, in the defence of Rome against an attacking French army.

[12] Its economic significance was somewhat greater, as the hill's interior was discovered to have unusual cooling properties which investigators attributed to the ventilation produced by its porous structure.