These gigantic constructions are the primary way of traveling very long distances. Interstellar distances are so vast that D-drive travel would take hundreds or thousands of years to reach Reyalian space.A gate is actually a set of three concentric rings with each rotating a central point. The rings are huge, with diameters of ~1,300 km, ~2,100 km, and ~3,400 km. Each ring appears to be constructed of one smooth piece of whatever material the thing is made out of. Analysis has been hampered by the fact that they seem to reflect any energy directed at them.
The closest Gate was found as the only notable object orbiting Tau Ceti. Researchers concluded that the contents of the star system had been dismantled to provide the raw materials to construct the gate. This type of stellar engineering is far beyond the ability of any race thus encountered (including the Reyals).
The Gates seem to have been built as a transportation network by the Precursors. The gates work in pairs, always moving ships from one gate to another. Oddly enough, only crewed objects seem to be able to travel between gates. Unmanned probes are deflected away without damage.