The marks of stonecutters did not begin to receive any attention until the end of the XIX century due to the studies of Franz Rziha (Bohemia 1831- 1897). It is completely impossible in this small article to cover the complexity of this symbology, as the studies have not yet been completed. It seems that the most accepted hypothesis is that of Viollet le Duc, in which he explains that most of these signs are marks belonging to the various Guilds that intervened in the work, as well as those of the stonemason indicating the job done and to determine the corresponding salary. Others like those of settlement that consisted of small signs in order to determine the points of placing or the beginning of the position of a row of stones. Each Guild had a master builder, and each master his trademark, which was usually placed on visible sites of the construction, such as the vault key of the portal, the cruise of the warhead, on the capitals, etc. ; we can also find it on the shields, or inscribed in the architecturally remarkable objects. For the man of the Middle Ages the whole universe was a system of geometric symbols, the symbol to him was not an aesthetic manifestation, but it was rather a vital reality. The procedures of the design of the diferent cathedrals, were the same. The descriptive geometry the so-called sacred geometry, is based on the compass that designates the circle, the arch of the circle that delimits and divides proportionally, the square representing the need for the right angle, the level and the plumb line that represent respectively the horizontality and verticality of the work. The basic shapes were the circle, the triangle, the square, the pentagon, the hexagon, the heptagon, the octagon and the dodecagon, and it is based on these three fundamental shapes the circle, the triangle and the square, that the most elaborate Gothic buildings are born. Each master builder had his own seal, based on these three fundamental shapes that formed a trilobate or a quadrilobate. The master traced his mark upon this basic figure, generally very elaborate, and the rest of the marks of the components of the Guild were only small parts taken from the basic and principle figure. One can find other signs or figures, which could be signs of pilgrims, meeting points or others without any apparent significance..