New insights on the structural weakness of the Duomo Nuovo in Siena

In 1339 while the work to enlarge the transept and apse of the cathedral was still in progress, discussions started on the construction of the Duomo Nuovo. This ambitious project proposed the construction of a new basilican body orthogonal to the existing building, transforming it into a transept. Work continued for thirty years until 1357. The structures were then in imminent danger of collapsing and experts advised the demolishing of the vaults and pillars. The project was thus abandoned. Work recommenced on completing the apse and transept, determining the configuration which exists today. Today, only a nearly the totality of the flanks of the Duomo Nuovo and the Facciatone survive. Moreover part of the eastern aisle hosts the Opera of the Metropolitana Museum. Investigation of the remains of the lateral aisle, of which the vaults, pillars and outer sidewall survive, help us to understand the type of structure flanking the vaults of the central nave, as well as the deformation they caused on the support walls. These are eloquent traces of distressing moments during the construction of the Duomo Nuovo, when renouncing the grandiose project and eventual demolition of large parts of the unsafe structure became inevitable. This data helps us to understand the conditions of vulnerability which led to such a fatal outcome.