Black Sepulchre

The Black Sepulchre is the underground temple that connects several Gardens of Morr within the Imperial city of Altdorf via a network of elaborate catacombs.

History
Long ago, some of the dead of Altdorf were buried in a network of underground passages beneath the city’s Gardens of Morr. These catacombs survive to this day, filled with the bones of the longdead. Rumour has it that their most valuable possessions were buried with them, and some treasures are still to be found in the catacombs. This tempts many a brave or desperate adventurer down.

The catacombs link up several important Gardens of Morr within the city, including the haunted cemetery of Old Altdorf. Stories say that there is an underground temple, the Black Sepulchre, at the heart of the catacombs. The complex is said to be looked after by a secret order of Morrite Priests who, they say, never see the light of day. They spend their entire existence patrolling the catacombs and keeping the dead quiet. This is fanciful but it shows the sort of reputation that Morrites have that this is easily believed.

Source

 * Warhammer Fantasy RPG 3rd ED -- Signs of Faith pg. 10