On the acropolis in the Ionian city of Metropolis, stone projectile arsenals were excavated between 1998 and 2004. They date from the Late Hellenistic - Roman period. They testify to self-defence measures undertaken by a city situated at an important point in the region's transport network. The stone balls are what remain of a battery of artillery which most probably also included bolt and dart machines and was concentrated on the acropolis - to judge by the surviving inventory and by the strategic constellation of the locality. The surviving stone projectiles indicate that the artillery pieces had a calibre of 5 to 15 mines, with 10-mine torsion devices being the preferred type of ordnance. For financial reasons and particularly for reasons of military know-how, the small city of Metropolis was dependent on outside help for the installation and maintenance of such a battery, and thus it can be assumed that material, financial assistance as well as expert personnel were made available by the regional power. The latter may have been the Attalids or alternatively local representatives of Rome during the civil wars. It is an established fact that support of this kind was practised elsewhere.