I use Astronomy Picture of the Day for backgrounds. Check them to make sure you are using copyright free images from there.

The menus I use could get very cumbersome which is why I decided to combine similar topics.

Those are wall placing/creating commands.

If you want to edit the width of a wall:

changelw is the command, change line width is what it means.

to make sure I just select the Wall, I go under layers and freeze all with a check on the walls layer.

right click, select Do it.

type in the new width, it will show on the bottom line of the software.

press the Enter key. You now have a new line/wall width.

Any hanging macro, type selbyd <enter>

That will close the macro so you can continue with something else.

It could depend on what the characters knew.

Ancient ruins, with say a 20th century city nearby for the tourist trade that is now gone, could lend themselves to a post apocalyptic world. A burned out bus or two, near an Aztec or Mayan pyramid.

Demolished metal that was once a car, next to a Greek or Roman stadium, stone housing, and temples.

That is what I would do.