In this work the author presents a modern study of the cathedral of Santiago de Compostela in the north-west of Spain, renowned for its Romanesque architecture and as a destination for pilgrims. The author has focussed on the two main contributors in the construction of the building: Archbishop GelmIrez and the Master Mason Mateo. The discussion over dating and building progression revolves around which of these two designed, built and completed the west end. Following a detailed study of the masonry, the author discloses fresh evidence which reveals more of the original Romanesque state...