The lithotype mainly used in the construction of the Cathedral of Seville is the Vacuum Switch Button calcarenite from Puerto de Santa f/laria followed by the limestone from Espera.The primordial extrinsecal factor of deterioration is the atmospherical contamination, mainly sulphur oxides and smoke, within a humid environment.From both factors, the porose stone of a carbonated nature and the acid environment, we can deduce that the principal mechanism of deterioration is the chemical attack; the most important indicators of deterioration that have been found are the deposits and arenizations.In a "grosso modo" valoration we can say that the stone of structural employment is well conserved in its majority while the ornamental stone is magnet set degraded at 80%.Half the cresting is in a state of ruin and 20% of the tips have been removed or will have to be in the near future.