ancientegyptdaily:

Original Entrance
The original entrance of the GREAT PYRAMID is located on the north side, 7.9m east of the centerline of the pyramid. Before the removal of the casing in the middle ages, the pyramid was entered through a hole approximately 17m above the pyramid’s base level. A row of double chevrons diverts weight away from the entrance. Several of these chevron blocks are now missing.

Robbers’ Tunnel
Today tourists enter the pyramid via the Robbers’ Tunnel, which was long ago cut straight through the masonry of the pyramid. After running more-or-less straight and horizontal for 27m it turns sharply left to encounter the blocking stones in the Ascending Passage. It is possible to enter the Descending Passage from this point but access is usually forbidden. According to tradition the chasm was made around 820 AD by Caliph al-Ma'mun’s workmen with a battering ram. Unable to remove blocking stones, however, the workmen tunneled up beside them through the softer limestone of the Pyramid until they reached the Ascending Passage. Some evidence suggests that some sort of robber’s tunnel predated al-Ma'mun, and that the caliph simply enlarged it and cleared it of debris. [X]

Diagram

• 1= Original Entrance
• 2= Robbers’ Tunnel
• 3= Descending Passage
• 6= Ascending Passage