Concrete World is an area accessible from the tunnel of the Highway in Onyx Tile World.
Fetures
The basic landscape is simply orange/yellow blocks and grey concrete floor tiles with pipes sometimes sticking out of the ground. In Concrete World B (where you are transported to when you enter via the Highway), you can use the Fairy effect to make a flashing diamond appear. This will transport you to Concrete World A.
Concrete World was originally the main place where you could find the Spacesuit effect in previous versions of the game (The suit is actually still obtainable in the same place as it was). It was also the place where you could enter from going through the bottom doorway in the Museum. Now this (and all its other previous features) has been replaced by Flying Fish World. You can still travel up the elevators, but doorways that lead to particular places no longer work.
Connections
Highway
(Museum)