The Pit is a sublocation found within the central chamber of Gehenna in Shadow Man: 2econd Coming. Located beneath the floor of the chamber, The Pit is the prison in which Asmodeus waits impatiently for freedom.
The area is a giant domed room with Grigorian symbols on the ceiling. It acts as a hub for the entire adventure. From this area, Shadow Man can reach the Dark Sepulchres located around the world to face the Grigori as well as access the further reaches of Gehenna.
The area later acts as the location of the final confrontation between Shadow Man and Asmodeus.
(from Shadow Man 2econd Coming Game Scriptment and Strategy Guide)