section_path: Interior/King's Chamber/Air shafts
section_name: Air shafts
paragraph_text: Air shafts
  
  In the north and south walls of the King's Chamber are two narrow shafts, commonly known as "air shafts". They face each other and are located approximately 0.91 m (3.0 ft) above the floor, 2.5 m (8.2 ft) from the eastern wall, with a width of 18 and 21 cm (7.1 and 8.3 in) and a height of 14 cm (5.5 in). Both start out horizontally for the length of the granite blocks they go through before changing to an upwards direction.
  
  The southern shaft ascends at an angle of 45° with a slight curve westwards. One ceiling stone was found to be distinctly unfinished, which Gantenbrink called a "Monday morning block". The northern shaft changes angle several times, shifting the path to the west, perhaps to avoid the Big Void. The builders apparently had trouble calculating the right angles, resulting in parts of the shaft being narrower. Now, they both commute to the exterior. Whether they originally penetrated the outer casing is unknown.
  
  The purpose of these shafts is not clear: They were long believed by Egyptologists to be shafts for ventilation, but this idea has now been widely abandoned in favour of the shafts serving a ritualistic purpose associated with the ascension of the king's spirit to the heavens.
  
  The idea that the shafts point towards stars or areas of the northern and southern skies has been largely dismissed as the northern shaft follows a dog-leg course through the masonry and the southern shaft has a bend of approximately 20 centimetres (7.9 in), indicating no intention to have them point to any celestial objects.
  
  In 1992, as part of the Upuaut project, a ventilation system was installed in both air shafts of the King's Chamber.