Palenque. As structures were completed, typically extensive relief work was added to the layer of stucco. However, many lintel carvings have been discovered, as well as actual stone carvings used as a facade. Commonly, these would continue uninterrupted around an entire structure and contain a variety of artwork pertaining to the inhabitants or purpose of a building. Though not the case in all Maya locations, broad use of painted stucco has been discovered as well. Though the Maya did not use a specific measuring unit, their buildings were still proportioned according to the golden mean. For their homes, the Maya would begin with a square then use a cord or vine to measure the square corner to corner. Then by arcing the cord down, a new base length could be established based on the previous square. The new rectangle's length would be the square root of two, which is a proportion found in nature. Since the Maya had religious connotations for which proportions they used and when, their form of measurement is called sacred geometry. It was also practiced by the Egyptians. The Maya played with different proportions in their temples and homes to yield symmetrical and harmonious designs all without the use of actual units. It has been suggested that, in conjunction to the Maya Long Count Calendar, every fifty-two years, or cycle, temples and pyramids were remodeled and rebuilt. It appears now that the rebuilding process was often instigated by a new ruler or for political matters, as opposed to matching the calendar cycle. However, the process of rebuilding on top of old structures is indeed a common one. Most notably, the North Acropolis at Tikal seems to be the sum total of 1,500 years of architectural modifications. Building materials The Maya civilization used very simple tools for building their structures. The most common tools use were made of stone found in surrounding areas. Limestone was a huge part of the Maya tool making, as limestone was geographically very abundant in most settlements. Locations of the Maya cities were chosen with the access to necessary stones in mind. This allowed most quarries to be right outside the city for easy access to blocks needed for construction. Top limestone quarries used were Palenque and Tikal. Though limestone was the most important material, they still collected sandstone from Quiriguá and volcanic tuff from Copan. The Maya people had taken advantage