Roland Deschain and his fellow Gunslingers, alongside Marten Broadcloak, witness the city crumble from a Beam-Quake. The first Beam to fall was the Eagle-Lion beam, which ran straight through Gilead. The Great Road, uncovered by them as they walk Southeast along the path of the beam, is built in the direction of of the beam which leads them to the city of Lud. Trees grow in the direction of the beams, even their shadows follow the direction of the beams. The ka-tet are able to see the beam at work, by seeing birds turn to follow the beam as they pass through it. Once Roland, Eddie, and Susanah reach the portal of Shardik, Roland demonstrates the power of the beam through using a crude compass. 'All things serve the Beam' is a common theme throughout the story. When between the turtle and tower, it is the beam of the turtle, path of the bear - even though the beam of the turtle, and the beam of the bear are the same beam. The spoke one is traveling can be described using the animal names in the following manner - the beam that goes bear - tower - turtle, when on the spoke between the bear and the tower, you are on the beam of the bear, path of the turtle. Though there are 6 beams, in effect there are 12 spokes - the Tower is at the centerpoint of each beam, and an animal guardian at each end. The Old Ones sought to replace the magical beams with their own technological versions and North Central Positronics created actual giant cyborg guardians.

At the end of each beam where a guardian resides, there is also a portal to another world. In all there are 6 beams and 2 guardians on a beam: bat, lion, bear, horse, rat, wolf, hare, eagle, turtle, dog, fish and elephant. The Beams are represented by 12 figurative 'animal guardians'. Like the Dark Tower, they are infinitely old, created at the beginning of the Universe and are themselves living entities (all male and brothers), having arisen from the Prim. Beams are physical forces that hold up the Dark Tower.

Shardik bear