The route takes you around the perimeter of Manhattan island in New York. You can start anywhere on the perimeter. On the west side of Manhattan you can follow the Hudson walkway all the way, then loop along the tip of downtown by Battery Park walkway and past the Staten Island ferry stop, this then connects with the East river walkway which takes you all the way up the East side. Then run all the way up to 125th on the east side, cut into Adam Clayton Powell and run north until it dead ends. Take a left on 155th and pick up the Harlem River Drive bike/pedestrian path (on your right). That will take you all the way to 10th Ave in Washington Heights. Run up 10th Ave to 218th St. Take a left and run straight into Inwood Hill Park. Then the path should run under the Henry Hudson Bridge and pick up the Hudson River Greenway on the west side and all the way back down to the start. 50km.
Going to make an unsupported attempt for this FKT tomorrow evening. I hate the heat, so we'll see how this goes...
Failure! Heat 1, me 0