The Windley Key Fossil Reef Geological State Park is a state park in Islamorada, Florida. It features the old quarry site established by Henry Flagler for his Overseas Railroad during the early 1900s.

The Windley Key Fossil Reef Geological State Park used to produce various materials for the construction of Flagler?s projects. The materials produced from this site were used for the track beds. Work on the quarry continued until the 1960s, despite the end of Flagler?s reign in Florida. The quarry mostly produced decorative stone pieces known as Keystone around this time.

Today, visitors can explore around the old site and view exposed sections of fossilized coral and original quarry machinery. Guests could also walk along quarry walls and learn about the operation of the quarry in the older days.