From Elf Sternberg's "The Journal Entries of Kennet R'yal Shardik, et. al., and Related Tales".

The longest road in the known universe, the Spinward March travels in a straight line (except for the curvature of the ring) from Castle Shardik to D'Tangent Arcology, a distance of approximately five million kilometers (5 gigameters), or 2 degrees around the ring. Along the way it goes through the town of Rocchodain, and "vast mix of wildernesses and climates" (Geographic: Public Spaces, 287/0100). According to Ken The March is "a joke".

    Travellogue, Day 6, 188/0916
Every fifty years they hold a vehicle race. The rules are simple. It has to be an internal combustion vehicle, it has to have an organic driver, although drive by wire is permitted, and it has to cross the finish line with one component the same as when it began.