Osireion - is the underground building,
adjacent to the western wall of the Temple of Seti I at Abydos. Osireion was discovered by archaeologists Flinders Petrie and Margaret Murray, who excavated the site in 1902-1903. Only in 1914 Osirion was
cleared from sand. The level of the Osirion floor is about 8 meters below the Temple of Seti I. Professor Neville ( Egypt Exploration Society) said, that Osirion is one of the most ancient buildings of Egypt.