Arguably the most common form of transportation between the Known Lands. The Great Arch arch consists of two large hills on either side of the road, with large, white, ancient-looking towers extending out of the hills towards the sky, with the sky forming the "top" of the arch.
This never made much sense to Alex because it doesn't look like an arch, but he can't deny it works. You simply walk through the valley between the two hillsides and you will find yourself in a new land.
In Telous, the Great Arch is about four hours normal ride away from the Golden Swan or two hours hard ride. It is in the wild lands of Telous. Few people live near a Great Arch, because it is shrouded in mystery.