The substructure access is located slightly above ground on the pyramid's north face. A short descending corridor – lined with granite – leads into a vestibule, beyond which the route is guarded by a pink granite portcullis, with granite lined walls on either side. The corridor is long sloped at 24° 48′, with a passage wide and high. The corridor following – lined with limestone – begins with a slight ascent becoming horizontal – lined with granite – just prior to its terminus. The ascending portion is long with a slope of 5°, whilst the horizontal section is long.