Five of the twenty-four Romanesque churches built in the Vall d’Aran between the 11th and 13th centuries were planned according to the solar equinox through the use of techniques inherited from antiquity. This is the main thesis of the study entitled “Cosmology and Precision in the Vall d’Aran”, published recently by the director of the UIC Barcelona School of Architecture, Josep Lluis i Ginovart, and lecturers Cinta Lluis Teruel and Iñigo Ugalde, in the scientific journal Nexus Network Journal. 

The researchers analysed the orientation of the twenty-four Romanesque churches in the Vall d’Aran by using a terrestrial laser scanner and computer software that allowed them to develop a highly perfected 3D model for each of the temples. This technique allowed them to check the high degree of accuracy of the layout of five churches in particular: Santa Eulària d'unha, Santa Maria d'Arties, Sant Pèir de Betlan, Sant Andrèu de Casau and Sant Miquèu de Vilamòs. All of them were traced out, on their central axis, according to the solar equinox and in a very precise manner. This research project indicates that the mountainous topography of the located where these temples were built makes it impossible to achieve a direct vision equinoctial orientation which, according to the study, would demonstrate that instrumental systems devised in classical times by Vitruvio, Hyginus Gromaticus, Gisemundus and Gerbertus Aureliacensis were used.  

A second study led by the same researchers also notes the differences between the Romanesque churches in the Vall d’Aran and those in the Vall de Boí. Therefore, in the research project entitled “Gisemundus and the orientation or the Romanesque churches in the Spanish Pyrenees (11th - 13th centuries)”, published in the Mediterranean Archaeology and Archaeometry scientific article, the high level of precision of the five churched in the Vall d’Aran is once more pointed out, in contract to the nine temples built in the Romanesque period in the Vall de Boí.  The researchers conclude that, while it is not possible to determine exactly which method was used for the orientation of the churches of the Vall d’Aran, it is most probable that the classical Ars Groematica Gisemundi method was used. It was already widespread in southern France and in Ripoll during that period.