City of Jetstone
Jetstone was the original capital site of the Jetstone side. Despite Jetstone (the side)'s ability to defeat Spacerock (the side) by conquering Spacerock (the city), Jetstone (the city) paled in comparison the the opulence and grandeur of Spacerock (the city), thus prompting Jetstone (the side) to move its capital to Spacerock (the city).
Jetstone could be the 3rd level 5 city in the side, and Spacerock was just more appealing, or perhaps it is lower level and they just didn't bother to upgrade it. At any rate, it's probably at least level 3 or 4.