Start at Brookyln Bridge on the Manhattan side and finish at the end of the GW bridge on the New Jersey side as fast as possible, but have to cross all of Manhattan's bridges in the process. There are 17 bridges with pedestrian paths and this route cross all of them, there are a few train / car only ones that were excluded.
There is no set route since there is so much construction and detours in NYC so its a bit of an adventure to figure it out on the fly. As long as you cross all of the bridges that connect Manhattan to other land it works! Think it would be cool to not have a set route since construction and detours would always change up the best approach.
I did this route in the GPX attached in a total time of 4 hours, 22 minutes and 5 seconds. Thinking this route could easily be shortened by a mile or two if someone was more familiar with the city. I just did this randomly since I always run across the Williamsburg bridge and was wondering if running across all of them was possible.
Hope this works! Was a fun route to see most of the city, hits 4 of the 5 boroughs too!