In this article, we present a robot capable of autonomously traversing and manipulating a three-dimensional (3-D) truss structure. The robot can approach and traverse multiple structural joints using a combination of translational and rotational motions. A key factor in allowing reliable motion and engagement is the use of specially designed structural building blocks comprised of bidirectional geared rods. A set of traversal plans, each comprised of basic motion primitives, were analyzed for speed, robustness, and repeatability. Paths covering eight joints are demonstrated, as well as automatic element assembly and disassembly. We suggest that the robot architecture and truss module design, such as the one presented here, could open the door to robotically assembled, maintained, and reconfigured structures that would ordinarily be difficult, risky, or time consuming for humans to construct.