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 shards were laid down in some places, possibly to serve as paths for those carrying out the waste disposal operations.