But it took hundreds of people hours of mind-numbing planning sessions to do it back then. And they were humans, they did screw it up every once in a while.
No further Requirements. As many or as few paths as you'd like, no worries about efficiency, sure you can go through the same streets many times if it helps. But needs to cover every street, obey orientation, and be readable by others.
Does not sound easy, does it?
Now, let's add a few more Requirements...