Stairs of Cirith Ungol

The Stairs of Cirith Ungol were the means by which the pass of Cirith Ungol was accessed from the Morgul Vale, near Minas Morgul. The stairs consisted of two sections, named the Straight Stair and the Winding Stair respectively, cut into the western face of the Ephel Dúath. The stairs ran nearly vertically from the valley floor for hundreds of feet, ending in a cleft through which the path led through Shelob's Lair to Cirith Ungol.

History
The stairs' origins are unknown, but were known to be a treacherous place by at least the late Third Age. During the War of the Ring, in the year TA 3019, Gollum led Frodo Baggins and Samwise Gamgee up the stairs as a means to enter the land of Mordor undetected. Though little used, the Orcs from the Tower of Cirith Ungol were aware of the stairs' existence.