There have been seismic studies of the Sphinx's structure and underground of the area around it. Based on these, although, some have argued the existance of a man-made cavity under the Sphinx's right paw (Lawton & Ogilvie-Herald, 2001), but due to absence of direct archaeological activity, this has not been verified.

Cayce's claims regarding the Hall of Records have significant antecedents, particularly in pseudohistorical theories about Atlantis popularized by Ignatius Donnelly in the late 19th century. Additionally, medieval claims about hidden passages at Giza contributed to the narrative. In the 1990s, these ideas were further intertwined with fringe hypotheses about the origin and age of the Giza monuments, such as the sphinx water erosion hypothesis and the Orion correlation theory. Advocates of these theories adopted Cayce's suggested date of 10,500 BCE for the origin of the sphinx, anticipating that the Hall of Records might be uncovered and lend validation to occult and New Age beliefs. Despite extensive exploration, including the investigation of a tomb known as the "water shaft" in 1999, no evidence supporting Cayce's description has been found.

circa 2500 BCE

The "Hall of Records" is described as a subterranean structure purported to exist underneath the Great Sphinx of Giza, Egypt. According to claims made by Edgar Cayce, the hall is situated between the Sphinx and the Nile River, with its entrance near the Sphinx's right paw. The hall is believed to house records from both Atlantean and ancient Egyptian civilizations, containing written materials in their respective systems of writing. Cayce further suggested that the hall might be pyramid-shaped and constructed around 10,500 BCE, aligning it with his broader narrative of Atlantean refugees influencing early Egyptian civilization.

The idea of the Hall of Records' existence under the Great Sphinx of Giza is entwined with earlier depictions (inspect) of the Giza Plateau. H.C. Randall-Stevens and Harvey Spencer Lewis provided diagrams and descriptions of an intricate network of subterranean passages and chambers beneath the plateau. These works included depictions of areas where mystical teachings and initiations were allegedly conducted, contributing to the mythos surrounding the Hall of Records. Randall-Stevens claimed to channel his descriptions from spirits, while Lewis derived his accounts from esoteric traditions linked to the Ancient and Mystical Order Rosæ Crucis.

Scientific investigations have aimed to identify any structures resembling the Hall of Records. Ground-penetrating radar and seismographic surveys identified anomalies in the rock beneath the Sphinx's paws. However, drilling and subsequent explorations only revealed natural cavities and fissures. These findings failed to corroborate the existence of a man-made structure matching the descriptions provided by Cayce or earlier speculative accounts.

The broader myth of the Hall of Records also intersects with other fringe theories, such as the Sphinx water erosion hypothesis and the Orion correlation theory. These theories have sought to redate the Giza monuments to periods earlier than conventionally accepted. Proponents like Robert Schoch, Graham Hancock, and Robert Bauval have drawn connections between these ideas and Cayce's predictions, speculating about transformative discoveries that could impact global understanding of history. However, mainstream archaeological consensus has dismissed these claims due to the lack of evidence supporting their hypotheses.

circa 2500 BCE

Several tunnels and cavities have been identified within and near the Great Sphinx of Giza. These structures have been the subject of much speculation, although their origins and purposes remain debated. Mark Lehner and Zahi Hawass, leading Egyptologists, have confirmed the existence of three tunnels associated with the Sphinx. The first, discovered in 1937 CE, is situated above the statue's back. Another tunnel was found on the statue's northern side, and a third, located beneath the Sphinx's chest, was excavated in the early 19th century. These tunnels appear to have been primarily explored by treasure hunters, with no conclusive evidence of hidden chambers or treasures reported.

Additionally, some researchers have posited that naturally occurring fissures may exist beneath the Sphinx, potentially expanded by ancient quarrying. Explorations in recent decades, including ground-penetrating radar studies, have revealed anomalies that might suggest voids or cavities beneath the monument, although their significance is unclear. Despite numerous theories, including connections to mythical archives or libraries, no substantial archaeological evidence supports such claims​