Short answers, pulled from the story.
The Amduat is an ancient Egyptian funerary text from the New Kingdom that describes the nightly journey of the sun god Ra through the twelve hours of the underworld, from sunset in the west to sunrise in the east. It was carved on the internal walls of royal tombs and served as a guide for the deceased pharaoh to follow Ra through the underworld and achieve rebirth.
Until the Twenty-first Dynasty, the Amduat was reserved almost exclusively for pharaohs and very select members of the nobility. One rare non-royal exception was Useramun, the vizier of Thutmose III, whose tomb included only hours three and four rather than the full twelve-hour journey. At the end of the New Kingdom, the text became more widely available, appearing on coffins and papyri for people of lower social rank.
The earliest complete version of the Amduat is found in KV34, the tomb of Thutmose III, located in the Valley of the Kings. Earlier fragments appear in the tombs of Hatshepsut and Thutmose I (KV20), Thutmose I (KV38), and Thutmose II (Wadi C-4).
The Amduat is arranged in three continuous horizontal registers, with vertical registers of text separating each of the twelve hours. Each vertical register names the hour, the gateway connecting regions, and the name of the underworld territory. The middle horizontal register traditionally begins with Ra on his solar barque entering a new realm.
Maat, the goddess of truth, order, and control, appears throughout the Amduat journey beginning in hour one, where two depictions of her lead Ra's barque. She represents the order that keeps the underworld's chaos in check, particularly in hour five where the waters of Nun and the desert sands of Sokar collide. At the end of the journey, the deceased pharaoh faces the Weighing of the Heart ceremony in the Hall of Maat.
Historians Catherine Roehrig and Barbara Richter have argued that the curved, bent-axe architecture of Thutmose III's tomb was designed to mirror the labyrinthian structure of the underworld as the Amduat describes it. The tomb slopes downward, begins on the west side of the burial chamber, and ends on the east side, echoing the sun's path from sunset to sunrise.