Tip: You can use Lunar Magic's Overworld Layer 3 Editing system to edit or create your own layer 3 images (castle bricks, fish, rocks) and apply unique effects per level via the Layer 3 Bypass in the main editor.
This is Blackheart Beat, Popla Cocapetri's stage theme from Megaman Zero 4. Not a theme I've always been very fond of (mainly because of how annoying the boss associated with this theme is, along with the stage itself being kind of a pain), but definitely grown to love it more as time went by. lol
Anyway, this should be pretty good for castles, factories, fortresses, or any other kind of "facility" type of themes. Naturally, it could also fit urban settings just as well.