Rendezvous with Rama · Arthur C. Clarke, 1973
How long is the stairway down into Rama?
8km
Ladders, then a stairway curving 8 km down from the hub to the plain. Nearly the height of Everest.
From the bookReal world
There are three identical stairways, 120° apart, like the ribs of an umbrella. Karl Mercer's party takes Stairway Alpha.
At the top they weigh almost nothing. The stairway gets steeper as gravity builds, and by the bottom they are braking rather than climbing. At the foot they set up Camp Alpha on the plain, at 0.6 g.
Go down Stairway Alpha