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At the upper end of the Gallery, on the eastern wall, is a hole near the roof that opens into a short tunnel by which access can be gained to the lowest of the Relieving Chambers.
The floor of the Grand Gallery has a shelf or step on either side, 1 cubit (52.4 cm; 20.6 in) wide, leaving a lower ramp 2 cubits (1.0 m; 3.4 ft) wide between them. There are 56 slots on the shelves, with 28 on each side. On each wall, 25 niches have been cut above the slots.[164] The purpose of these slots is not known, but the central gutter in the floor of the Gallery, which is the same width as the Ascending Passage, has led to speculation that the blocking stones were stored in the Grand Gallery and the slots held wooden beams to restrain them from sliding down the passage.[165] Jean-Pierre Houdin theorized that they held a timber frame that was used in combination with a trolley to pull the heavy granite blocks up the pyramid.
