The first example with which I would like start consists of the construction of the ribbed vault that appears in the manuscript of Alonso de Vandelvira from the 16 th. century. It represent a vault never built and here you have the original drawings from Vandelvira, in them we can see the height level of the geometrical representation, the plan and the elevation as been designed using the modern geometrical tools in order to determine de most important data of the vault.(photo 1a y 1b).

The study of this drawings allows us to discover the most interesting feature of this vault: in fact it is a spherical vault: So, the intention of Vandelvira is to show us that a gothic ribbed vault could also take a spherical shape and show us the way to built such curious vault (photo 2).

The volume of the sphere defines the height of the central boss stone and, consequently the curvature of the diagonal arch that must bee one semicircular arch. The sphere also sets the height of the others main boss stones and, in the same way, the curvature of the others ribs: the tierceron arches and the formerets. So, the construction of a ribbed spherical vault requires that the three main arches must have different curvatures. This specific feature of this vault makes the construction of the vault a little bit more complex, as each arch has to be segmented in voussoirs, each arch must have its specific voussoirs carved whit its accurate curvature (photo 3). (foto 3). [....]

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