Nardol was the third Beacon of Gondor. It stood on the broad end of a ridge of the White Mountains, and the guard station maintained there could create a huge signal fire when needed. It was well-stored with fuel and at need a great blaze could be lit.
Its fire could be visible on a clear night even as far as the Halifirien (some 120 miles to the west)
The guard also protected the quarries.
The previous Beacon on Eilenach came to a sharp point, making the building of a bright beacon difficult.