The Expository Bridge is a three-arch stone bridge across a river in Jetstone. It is the last major defensive point between Gobwin Knob (formerly Unaroyal) territory and Spacerock, the Jetstone capital at the beginning of Love Is A Battlefield. It is the location of the Battle of the Expository Bridge.
Real World References
An expository bridge is the use of direct exposition to link one chapter of a story to the next one: exactly what is happening when the bridge is introduced.