From this angle, one might think that most of Joliet, IL lay in ruin. I guess that's not the case, but even one of the casinos burned down!
The historic Joliet prison was completed in 1858 for a total sum of $75,000 (and convict labor). Designed by William Boyington, the same architect who designed the Chicago Water Tower (you'll note the similarity), the prison is built of limestone quarried directly from the site.
The nearby Joliet Ironworks, in the foreground, was abandoned in the 1930's. Overgrown and forgotten until recent years when it was turned into a park along side of the Illinois and Michigan Canal National Heritage Corridor.
There are lots of fun ruins to explore at the ironworks, and some you need to stay away from due to loose bricks. The underground tunnels are interesting, leading from one blast furnace to another.