Soleanna

Soleanna is the City of Water, and the main location of Sonic the Hedgehog. The city is a monarchy, ruled by a king, queen, or prince/princess, and is shown to have highly advanced technology, as shown in the Aquatic Base level. The city worships a deity known as Solaris, and is currently ruled by Princess Elise.

It is possible that the Crisis City level is the Soleanna of Silver's world, though it seems somewhat unlikely, as Soleanna does not seem to have any automobiles, which are prominent in Crisis City.