Through the rear door of the temple is the Osirieon, the only visible tomb at this site, which was built before the main temple. Much of the damage to the Osirieon has been from flooding, as it was built at water level, yet it is not much diminished. Red Aswan granite pillars, each weighing about a hundred tons apiece, support equally massive archways. This temple was built as a symbol of Seti's closeness to Osiris and contains a sarcophagus, though Seti was not buried here. Seti's actual tomb is in the Valley of the Kings in Luxor. This was a fairly common practice among many of the pharaohs, having "public" tombs in one location, but actually being buried in another. The Osirieon is currently inaccessible because of the rising sand and the flooding that has occurred. Excavation has been done on the south side passage, which revealed texts from The Book of the Gates and The Book of What is in the Duat. This section was begun by Seti and finished by his grandson, Merneptah. It is a complete tomb structure, all ready to receive the mummy of a king, yet it does not appear ever to have been used so.

Abydos does have a reputation for these "false tombs" or cenotaphs. Some theorists state that Abydos does not even have a single actual tomb in it, but that all the dead who have tombs at Abydos are actually buried elsewhere. The cemeteries of northern Saqqara certainly have a great number of royal mastabas, of which many have been linked to the Archaic rulers.