The Osirion or Osireon is an ancient Egyptian temple
It is located at Abydos, to the rear of the Mortuary Temple of Seti I. The Osireion is a weird and wonderful structure, unique in Egypt and still baffling for Egyptologists
A rectangular island in the center of this hall had receptacles carved into its floor to receive a sarcophagus and canopic chest.
Upon the island were built massive pillars made of five Aswan rose colored granite monoliths about 2.4 meters square by a little over 3.5 meters high and weighing, on average, around 100 tons, to support the ambulatory atop the equally massive architraves.
There is some evidence that the structure may have originally been completely roofed with monolithic slabs. A channel about three meters across then surrounds this island.
It contained water and thus the interior of this structure was symbolic of the primeval waters of creation from which an island arose. At either end of the island stairways lead down into he water channel about 3.5 meters.
The outside walls of the structure, made of red sandstone some six meters thick, contain six unfinished niches on each of the room's long sides, three more on the wall facing Seti I's temple, and three more on the opposite wall. Around those were a ledge forming the outer edge of the water channel.