Construction notes on the lost dome of Montecassino basilica

In the early 17th century the basilica of Montecassino Abbey, which had already seen architectural transformation, work began on the construction of the dome based on designs by the Roman architect Orazio Torriani, a member of the Accademia di San Luca. Analysis of signed letters and the report on “Misura et stima” held in the abbey’s archive, indicate important aspects of construction. The contents of the letters and report contributed to the debate between leading architects of the period on the value of chains in dome construction, a common device in the Rome area between the late-16th and mid-17th centuries. Analysis of the dome using a 17th century survey of the abbey shows formal geometric adherence to the construction “regole” of the period. In addition, drawings for the project made by the engineer Giuseppe Breccia Fratadocchi illustrate the new geometric conformation of the then current dome, which was rebuilt after bombing during the Second World War.