Keystone is a type of limestone, or coral rag, quarried in the

Florida Keys The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...

, in particular from

Windley Key Windley Key is an island in the upper Florida Keys in Monroe County, Florida, United States. U.S. 1 (the Overseas Highway) crosses it at approximately mile markers 84–85.5, between Plantation Key and Upper Matecumbe Key. All of the key is within ...

fossil quarry, which is now a

State Park State parks are parks or other protected areas managed at the sub-national level within those nations which use "state" as a political subdivision. State parks are typically established by a state to preserve a location on account of its natural ...

of Florida. The limestone is Pleistocene in age, and the rock primarily consists of scleractinian coral, such as Elkhorn coral and Brain coral. The Hurricane Monument, commemorating victims of the Labor Day Hurricane of 1935, and located at mile marker 82 on U.S. Route 1 near Islamorada, is constructed of keystone, as is the

David W. Dyer Federal Building and United States Courthouse The David W. Dyer Federal Building and U.S. Courthouse, formerly known simply as the U.S. Post Office and Courthouse, is an historic United States Post Office and federal courthouse of the United States District Court for the Southern District of ...

See also