Mackinac bridge
It connects the upper and lower Michigans. It crosses five miles and is the third longest suspension bridge in the world. (The other two both opened in 1998, so it had the record for a while.)
The time I crossed it, as a rider not a driver, it sure made *me* queasy.
See [link|http://www.mackinacbridge.org/|this site] for anything you'd like to know.
"Beware of bugs in the above code; I have only proved it correct, not tried it."
-- Donald Knuth