Have thought about adding a prison as a backdrop along the wall as Ralph mentioned.
Southern railway served a prison in Atlanta, GA. The prison even had its own trackmobile!
One track serves the prison's powerhouse. The other track serves the prison's 396,000-square-foot industrial division. On it there are a receiving dock for raw materials located outside the walls and a loading dock for finished products located within.
Southern's principal shipment inbound to the prison's industry is baled cotton about 150 carloads per year. From this, the prison's textile mill annually produces about six million pounds of cotton duck.
More info in an article
here with photos
Tom