You can’t see anything of the fort, today, (most of it is buried under tons of granite and marble beneath the George Rogers Clark Memorial](George Rogers Clark National Historical Park (U.S. National Park Service))), but Fort Sackville was way out on (what became) the Indiana - Illinois border in Vincennes, IN.
Where was Fort Bag End? 
ducking and running
Correcting myself: Fort Morris was not built by the British, but rather by the Americans.
I read the thread title that way too.
There are just some things Americans do best.