The Partial Collapse of the Basilica of Maxentius in Late Antiquity: An Evaluation of Possible Destruction Causes

Abstract

It is still commonly considered that the main collapse of the Basilica of Maxentius in Rome occurred in the Middle Ages, caused by one of the destructive earthquakes of those centuries. In this paper, the possible causes of destruction—for which, however, evidence can already be found in Late Antiquity—are systematically evaluated also in terms of co-seismically induced damages. Thus, it could be demonstrated that the building’s structure exhibited considerable deficiencies already during the construction phase. At the western wall of the central nave in particular, the lateral forces from vault thrust and earth pressure were apparently miscalculated in an almost reckless manner. Moreover, there is indication that static settlement effects have been seriously underestimated, especially in relation to the demolished and backfilled predecessor structures, the horrea piperataria, in the subsoil of the construction site of the basilica. These structural weaknesses were so severe that even small tremors or static shifts could have triggered the collapse, even more a major seismic event. And indeed, some horizontal fracture edges can be observed, particularly in the vaults, indicating a sudden lateral load impact as in an earthquake rather than a slow, steady settlement. Thus, the identified construction and settlement related deficiencies should have led to the basilica’s (partial) collapse at the first relevant change of specified loads. The earthquake of 443 AD is proposed and discussed here as the closest ‘suspicious’ event.