First Deep

Behind the main East-gate of Moria, the Dwarves had cut and tunnelled far into the rock of the Mountains of Moria. Their works extended upward into the heights of the mountains, and downwards into the depths beneath them. Floors above the level of the East-gate were referred to as simply as 'Levels', while those that extended down into the rock beneath were known as 'Deeps'. The First Deep, then, was the first tier of Old Moria that lay below the level of the Great Gates.

To one entering Khazad-dûm (as Moria was formerly known) through its East-gate, the First Deep was soon encountered. After passing first through the long First Hall that lay immediately behind the Gates, a broad stairway led downward into the First Deep. At the base of this stairway was the Second Hall, which contained the last defences of the realm of the Dwarves. A narrow stone bridge, the Bridge of Khazad-dûm, spanned a chasm of unimaginable depth, preventing enemies from entering the further halls in force. Beyond it, the Second Hall of the First Deep extended on into the mountain for more than a quarter of a mile.