Pidurangala is another massive rock located only a short drive away from Sigiriya...I suppose you could consider it Sigiriya's younger sibling. Pidurangala's importance actually dates back to the founding of the Sigiriya Fortress, when King Kasyapa forced the monks residing at Sigiriya to move to Pidurangala so he could build his spectacular fortress at the top.
At the base and entrance to Pidurangala, there is a nice if somewhat underwhelming cave temple featuring the same brightly-painted frescoes common in Sri Lankan cave temples. Then, you're in for an hour-long and somewhat arduous hike up the steep rock before arriving first at the Pidurangala Royal Cave Temple. Despite the grandiose name, the main feature of the temple is a long reclining Buddha that was gradually destroyed over the years by tomb-raiders and the elements and has been partially rebuilt in brick. If you look closely, you'll also note some faded frescoes on the cave walls above the reclining Buddha. Finally, you walk (and, at times, literally climb) around 15 minutes more through rocks, crevasses, and caves before arriving at the top of the rock. From there, you have spectacular views of Sigiriya and the surrounding jungles. Viewing Sigiriya from such height and distance really makes you appreciate what an incredible natural phenomenon it is.