Walls and floors are essential part of the Revive & Prosper.
You can organize all the Factories into massive building with multple floors.
This is how it works:
Walls are not on the block but on the edge of the block:
you can build walls on walls:
You can build floor at a distance 2 blocks from the wall without any support.
This way you can build balconies:
Columns support the floor.
To build something on the floor you must build it on the block supported by a wall or column OR is between two walls.
Walls, platforms & bridges can be built only on:
1) other walls or platforms
2) on floors that are between two walls
You can build multiple floors for buildings
The structure can go up 50 blocks so the buildings can be really tall.