Siena cathedral_The cathedral as a palimpsest of structures

Siena cathedral is an extraordinary example of architectural complexity understood as a concrete act of building, the result of several construction phases linked to countless specific conditions. It has unique genetic conditions. The orientation of the cathedral was dictated by the earlier cathedral, which for a certain period of time necessarily had to exist alongside the construction works to ensure continuity of worship. This placed the apse and transept on a slope and in a geologically distinct area given that it is at the edge of the fault line of a conglomerate bank. The works continued with the construction of the basilican body and later the domed space, with quite a few geometric adaptations. At the same time, it became necessary to make changes to the crypt and the apse by introducing two pillars into this space. This led to the completion of a cathedral, which turned out to be intermediate. The decision to build the Duomo Nuovo was made while the new apse was being constructed. There were also changes linked to accidental events, as earthquakes and fire.