Dots denote the major work at site. There may be sturctures from other periods at the same site.
French forts Spainish forts British forts USA Coastal: 1st & 2nd Sys. USA Coastal: 3rd System USA Coastal: Endicott USA Coastal: WWII Civil War Earthworks Inland and Others
French forts
Spainish forts
British forts
USA Coastal: 1st & 2nd Sys.
USA Coastal: 3rd System
USA Coastal: Endicott 
USA Coastal: WWII 
Civil War Earthworks
Inland and Others