Are the worlds made out of bricks like that?
The worlds look
like they are made of bricks, but they are actually interiors, just like the Bedroom or Kitchen maps. You can build on all of them and real bricks line up perfectly with them. Sometimes the color looks a little off, but to the casual observer it appears fine.
Also, if you'd like to have some weather, lava, and water in the map, load up the environment save I've attached to this post. The save will likely be improved over time so look out for more updates on that.