Talntower

The Talntower was an ancient dwarven waterworks that consisted of a spring-fed reservoir, channels, valves, and a collecting pool for drinking, watering animals, or bathing that was still in operation in the Year of Wild Magic, 1372 DR. It was generally thought to be haunted by a presence that whispered oracular pronouncements.

Geography
The Talntower was located on the west side of Jundar's Pass where the trail approached the hills almost 50 miles (80 kilometers) north of Beliard. A promontory of stone formed a rugged cliff about 70 feet (21 meters) high near the road. On either side of the Talntower, lesser cliffs continued north and south for a quarter-mile (400 meters) or more, and the minor plateau of solid rock extended for at least the same distance westward.

Features
The rounded prow of this natural formation, covered in vines and scrub, was unremarkable except for the enormous slab of rock that capped it like a gently sloping roof, and the cave entrance at its base. Long-forgotten dwarven engineers excavated down from the top of the cliff to create a reservoir for a spring that bubbled up from below. The oval-shaped bowl was about 35 by 70 feet (roughly 11 by 22 meters) in size and typically filled with eight to ten feet (2.4 to 3 meters) of water. The reservoir was quite deep, but could not hold more than about twelve feet (3.7 meters) of water because there were fissures in the eastern wall that prevented the water level from rising any higher. Some of these slits in the rock face had been widened by enough freeze/thaw cycles that a human could crawl through the eight to twelve feet (2.4 to 3.7 meters) thick wall and enter the bowl above the waterline.

Two drains, situated four to six feet (1.2 to 1.8 meters) up from the bottom of the reservoir, fed down small tunnels to the cave at the bottom of the cliff. To regulate the flow, each pipe passed through a valve made of a large stone slab that could be inserted or removed from the path of the falling water. The fit was tight enough to restrict the water flow to a mere trickle. When fully opened, the water gushed out rapidly for as long as it took the reservoir to reach the level of the lowest drain, and thereafter flowed at the rate of the feeding spring. The valve slabs were about a foot (30 centimeters) thick and the size of a human casket, complete with handles. It took at least three strong men to slide a plug stone out and four such men to push one back in.

The pool was the main feature in the cave, being about sixteen feet long, three to four feet wide, and four feet deep (roughly 4.9 by 1 by 1.2 meters). Above each end of the pool, water showered down from the ceiling where the drain tunnels ended, typically filling the pool to at least a depth of one foot (30 centimeters). The water drained from the pool through other natural fissures. On either side of the center of the pool were carved seating areas (or wading areas if the water level got too high). Set back from the entrance on each side were broad stairs carved into the cave walls that climbed about twenty feet (six meters) to chambers holding the valve-stones.