Sunset Park Zone did not originate from fanon, and more information can be found on their respective wiki(s). You may read more about it on the following wiki(s):

Sunset Park Zone
Sonic running through Sunset Park Zone
First Appearance Sonic: Triple Trouble
Location Type Trainyard
Sunset Park Zone is a location in the Sonic series. It made its first appearance in Sonic Triple Trouble, in which it is a transportation spastic for Dr. Eggman's nefarious schemes.

Fanon Appearances

Sonic Heroes 2

Sunset Park makes an appearance in Sonic Heroes 2. Here, all the mechapoly existent in previous carnations has disappeared, leaving nothing but a park behind. Many characters come here to relax sometimes, especially Honey the Cat. However, though fauna decorates ground level, it still has an underground that was left from when Eggman used it and is to this day accessible via train via Mystic Ruins North.