On the 'Outskirts' level, at the beginning, run forward into a passage with a blinking light. Duck-jump onto a light fixture and Duck-jump onto the roof. Notice a dark passage to your left about 90 degrees. Turn to your left 90 degrees. Again turn to your left 90 degrees, then run to the wall. Turn to your left 90 degrees again and jump over the gap. Now look at the wall to your right, duck-jump up here. Once here, run to the dark corridor then hop on the roof across the corridor. Now you are on the first roof. Explore more here. You can reach the hotel Zanzibar at the furthest.