 "The Book of Popes" mentions that Pope Anacletus built a "sepulchral monument" over the underground tomb of Saint Peter shortly after his death.This was a small chamber or oratory over the tomb, where three or four persons could kneel and pray over the grave.The pagan Roman Emperor, Julian the Apostate, mentions in 363 A.D. in his work "Three Books Against the Galileans" that the tomb of Saint Peter was a place of worship, albeit secretly.