Now lets make a wall around a circle at a distance of 1/2 mile. That's pixRx2. 3.14*2640'*2=16579'. For the moment, let's forget all the little angles and just stick square segments around this circumference. That's 1658 wall units, weighing 33160 tons.
Now let's repeat this, but for a wall at 1 mile. 3.14*5280*2=33158', 3316 wall units, weighing 66320 tons.
At 10 miles the wall would be 3.14*(10*5280)*2=331584', 33159 wall units, weighing 663180 tons.
These four walls hold (on the low end) contain 764780 tons of granite. Add another wall at 20 miles, and the total granite increases by another 66317 wall units weighing 7326340 tons. At five walls the granite is a total of 8,091,120 tons of granite. This is 404,556 cubic meters.
A 7th level wizard can shape 17 cubic feet, or about 1/2 a cubic meter. Therefore, it would take 809112 castings of shape stone to make the wall from easily transported rocks.
Should we see about acquiring visas, or are we sneaking over?
"My question is where are the firebenders and the gigantic drill? Oops, sorry, wrong anime."
Avatar: The Last Airbender
"I vote we just get visas. It's a hassle, but I just don't feel like being sneaky at the moment. It's pretty draining."
"Well, where do we want to start asking around? I'd do it myself, but I'm not so great with the information gathering. High bluff, low diplomacy."
The guards stand on either side of the open portcullis. As you walk through they glare at you, as they always do. You are emediately met by beggars off to the side. Not intrusive, but an eye sore. The stretch of row houses that blocks your vision are dilapidated. Despite all this, there streets are covered in bright colored streamers and the homes have tattered but bright banners for each of their own house.
"There some kind of festival going on I don't know about? Vaan says noting the decorations.
A begger hears Vaan. "mmawwww it's New Birth 'course. Spring's commin'." The foul smell of fermented mare's milk reached past his breath way farther than it should have.
The heroes stroll through town. People walking in fear, sitting on stoops, covered in dirt, and looking for food; all very usual.
It's not my forte, but I'm gonna see what kind of information I can find on these shipment attacks.
Vaan walks around, hesitant to question others, but finds himself speaking to a few. They all have much of the same to say. They have not seen any attacks, but they have heard of the monster killing people to the north.