I'm gonna finish up dead money and look for some things. Puesto del sol south is huge, where is this?

Wikia:

"Found in Puesto del Sol south. On top of the tallest roof found next to a group of drained microfusion cells. To get there, go into the cafe and exit through the top floor (exit located Southern part of cafe, not north or east) Follow the rooftops to the center building in the square and you will see grating leading to the platform above"