The northern entrance to the Pyramid of Khufu

The northern 

entrance to the Pyramid of Khufu

The northern entrance 7.9 meters east of the pyramid's central axis was accessible through a hole in the 19th layer of masonry approximately 17 meters above the base of the pyramid This 96-centimeter height corresponds to the size of the entrance tunnel which could have been lifted with movable stones to access the inclined passageway However it is unknown whether this was a later addition or an original feature Numerous graffiti mostly modern are carved into the stonework around the entrance The most striking feature is a large square hieroglyph In 2016 a cavity behind the entrance was discovered using muography a radiographic technique that uses muons to image the otherwise inaccessible interior

In 2019 it was confirmed to be a passageway at least 5 meters long and running horizontally or upwards not parallel to the descending passageway An endoscope survey of the passageway revealed a 9-meter-long horizontal tunnel and the cross-section of the passageway's ceiling formed a large V-shape similar to that seen above the original entrance resembling a relief chamber It is assumed to have been built to protect the pharaoh's chamber which likely collapsed under the weight of the rocks above

The tunnel's origins are widely debated Legend has it that it was opened around 820 AD by workers using ramming blocks The excavation uncovered rocks on the ceiling of the descending corridor obscuring the entrance to the ascending corridor The sound of falling rocks and tumbling down the descending corridor forced them to turn left Unable to remove these rocks the workers dug a tunnel up the side through the pyramid's softer limestone to reach a horizontal shaft connecting the end of the descending corridor to the basement. A recess forms the end of the western wall The ceiling is irregular and unadorned

From the descending corridor some debris from this operation is blown throughout the chamber. This deep modern shaft is sometimes mistaken for part of the original design The only chamber excavated into the pyramid's lower rock layers the basement is the lowest of the three main chambers oriented east-west It is unfinished with a deep trench left by the quarrymen extending from east to west. A channel is cut into the northern half of the western wall The only entrance is through the descending corridor Although it seems to have been known in ancient times according to the accounts the existence of this place was forgotten in the Middle Ages when the rubble blocking the passage down was cleared A vertical shaft leading down through the cave to meet the passage down