A bit of explanation:
The images above are from the FL DOC Road Prison on Big Pine Key. There used to be approximately 60 inmates housed who did basic road maintenance all up and down the Key's roads. The state decided several years ago that infrastructure repairs were too much to spend and closed the prison, contracting the roadwork out instead. The prison sits empty now.
The following are from the Big Blue Hole on Big Pine Key.
This now scenic stop is actually an abandoned rock quarry that was used for local roads and dug in the 30s and 40s.