The expansion of the Christian kingdoms through the Iberian Peninsula in the Middle Ages prompted a change in social norms and customs, resulting from the double process of conquest and colonisation. Architecture was one manifestation of the desires and needs of the new Christian society. This book examines the form, structure and construction of ecclesiastical architecture, taking as a case study the territory of the Sierra de Aracena, a region of the Kingdom of Seville conquered during the thirteenth century, by posing three questions: What historical and material constraints shaped the configuration of the churches? What was the approach to building them? And finally, what construction techniques resulted?To try to answer these questions the author embarks on a study of construction technique, drawing mainly on archaeological approaches such as geometric study of their floorplans, and here presents a complete survey, including 3D models that display the resulting information on the churches, which has been collated with reference to texts from a variety of archives.