section_path: Interior/Well Shaft and Grotto
section_name: Well Shaft and Grotto
paragraph_text: Well Shaft and Grotto
  
  The Well Shaft (also known as the Service Shaft or Vertical Shaft) links the lower end of the Grand Gallery to the bottom of the Descending Passage, about 50 metres (160 ft) further down.
  
  It takes a winding and indirect course. The upper half goes through the nucleus masonry of the pyramid. It runs vertical at first for 8 metres (26 ft), then slightly angles southwards for about the same distance, until it hits bedrock approximately 5.7 metres (19 ft) above the pyramid's base level. Another vertical section descends further, which is partially lined with masonry that has been broken through to a cavity known as the Grotto. The lower half of the Well Shaft goes through the bedrock at an angle of about 45° for 26.5 metres (87 ft) before a steeper section, 9.5 metres (31 ft) long, leads to its lowest point. The final section of 2.6 metres (8.5 ft) connects it to the Descending Passage, running almost horizontally. The builders evidently had trouble aligning the lower exit.
  
  The purpose of the shaft is commonly explained as a ventilation shaft for the Subterranean Chamber and as an escape shaft for the workers who slid the blocking stones of the Ascending Passage into place.
  
  The Grotto is a natural limestone cave that was likely filled with sand and gravel before construction, before being hollowed out by looters. A granite block rests in it that likely originated from the portcullis that once sealed the King's Chamber.