This requires you to go back where you began the game. If you're like me and don't recall where that was, here's where it's at. Make sure you have the Lightning Tether.
If you stand on the cement by the water, where the orange arrow is pointing is an electricity pole. Use the Lightning Tether to pull yourself to it, then follow the path of wires and bridges all the way back to the beginning. (There's also a Dead Drop back here.)
Map by Saveal. Originally posted infamous.wikia.com.