The Medieval Cathedrals of Europe all were built around the same time we are told. However whilst there are theories about how they were built, are there any precise details? For instance where and when did the architects and engineers gain their knowledge to build these huge buildings? What tools did they use to quarry, transport and then carve and erect the large stone blocks? Where did they find the large quantity of skilled labor at a time when we are told there was not a large population? Gloucester Cathedral may contain some clues: from huge stone columns with 'saw marks' to lofty vaulted ceilings, from a coat of arms including half of the 'survivors' double headed eagle to possible geopolymer castings with seemingly impossible stone carvings and tight joints in high quality masonry.