Monte Testaccio in Rome, July 2012

Monte Testaccio (alternatively spelled Monte Testaceo; also known as Monte dei cocci) is an artificial mound in Rome composed almost entirely of testae (Italian: cocci), fragments of broken amphorae dating from the time of the Roman Empire, some of which were labelled with tituli picti. It is one of the largest spoil heaps found anywhere in the ancient world, covering an area of 20,000 square metres (220,000 sq ft) at its base and with a volume of approximately 580,000 cubic metres (760,000 cu yd). It has a circumference of nearly a kilometre (0.6 mi) and stands 35 metres (115 ft) high, though it was probably considerably higher in ancient times. 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 mound later had both religious and military significance.

The huge numbers of broken amphorae at Monte Testaccio provides a vivid indication of the colossal amount of oil for food, as well as oil for lighting in lamps, that was required to sustain imperial Rome, which was at the time the world's largest city with a population of at least one million people. It has been estimated that the hill contains the remains of as many as 53 million olive oil amphorae, in which some 6 billion litres (1.3 billion imperial gallons/1.6 billion U.S. gallons) of oil were imported. 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. The vast majority of those vessels had a capacity of some 70 litres (15 imp gal; 18 U.S. gal); from this it has been estimated that Rome was importing at least 7.5 million liters (1.6 million imperial gal/2 million U.S. gal) of olive oil annually. As the vessels found at Monte Testaccio appear to represent mainly state-sponsored olive oil imports, it is very likely that considerable additional quantities of olive oil were imported privately.

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 shards to anchor them in place. Empty amphorae were probably carried up the mound intact on the backs of donkeys or mules and then broken up on the spot, with the sherds laid out in a stable pattern. Lime appears to have been sprinkled over the broken pots to neutralise the smell of rancid oil.

As the oldest parts of Monte Testaccio are at the bottom of the mound, it is difficult to say with any certainty when it was first created. Deposits found by excavators have been dated to a period between approximately AD 140 to 250, but it is possible that dumping could have begun on the site as early as the 1st century BC. The mound has a roughly triangular shape comprising two distinct platforms, the eastern side being the oldest. At least four distinct series of terraces were built in a stepped arrangement. Layers of small sherds were laid down in some places, possibly to serve as paths for those carrying out the waste disposal operations.

Text from: en.wikipedia.org/wiki/Monte_Testaccio