"looking through i saw (keenan's?)fire...but i don't know where is left for me to go"
The boot in question is the 1985-04-15, East Rutherford one.
Any helpful knowledge or speculation is welcome!

Edit: I would like to stress that it's an absolutely INSANE performance of the song. Even if you don't care about helping me you should listen to it.
REALLY!


), but if you can give it another listen and check the lyrics out, maybe we could find the song
We'll have to ask Bono himself
