Windley Key Fossil Reef Geological State Park preserves a former quarry in the Florida Keys where exposed fossilized coral and some original stone-cutting machinery remain visible. In the early 1900s, Henry Flagler worked the site during construction of the Overseas Railroad. After that project ended, the quarry continued producing decorative building stone known as Keystone. Stone taken from here was later used for the Hurricane Monument in Islamorada, tying the site to both the Keys' engineering history and a landscape formed from coral reef rock.