Oathgate
An Oathgate is an ancient device of the Knights Radiant that allows near-instantaneous travel across vast distances on Roshar in Brandon Sanderson's The Stormlight Archive. The Oathgates form a network linking major cities, with the lost city of Urithiru at its hub.
Function
Each Oathgate consists of a large platform inscribed with patterns, paired with a control building set off to the side. When activated by a Knight Radiant who turns the mechanism, everyone and everything standing on the platform is transported to the linked Oathgate at another location. The transfer briefly passes through the Cognitive Realm, Shadesmar, before arriving at the destination.
Activation requires the participation of a Surgebinder, which is why the Oathgates fell out of use after the Knights Radiant abandoned their oaths in the Recreance and the orders vanished. With the return of the Radiants, the Oathgates could once again be operated.
The network and Urithiru
The Oathgates connect ten locations across Roshar, including the Shattered Plains, Thaylen City, Azimir, and others, all radiating from the tower-city of Urithiru. This made Urithiru a strategic center, allowing the coalition of nations to move armies and supplies between distant fronts almost instantly. Control of the Oathgates became a key objective in the war against Odium.