Raffaele Davanzo briefly traces the history of the church, radically transformed over the centuries. A series of drastic demolitions altered many of its parts and destroyed many of its architectural decorations. Of particular gravity was the total demolition of the nave. This had grave consequences also for the tomb of Cardinal De Bray, which was dismantled and reassembled in the transept. The author postulates that the architecture of the church was planned in coordination with Arnolfo’s coeval design for the tomb, since both share fairly similar innovations in their conception of space. The type of church, among the most important Dominican realizations in the architectural field, is unique for its period; it is designed in a new way, to give the optical illusion of a church larger than it actually was. By a series of metric and perspective devices its single–nave interior was optically expanded beyond the limit of what was built, thus creating suggestive illusory spaces: an effect that was better perceived the further one advanced inside the church. The same criterion of perspective illusionism also characterises the De Bray funerary monument, in which the three–dimensionality evoked by Arnolfo confers on the tomb an illusionistic sense of space that makes it seem bigger than it actually is. The spatial correspondences between monument and church are complemented at the metric and compositional levels, as for example in the use of measurements that are multiples of the Roman foot.