After the dropdown at the beginning of the level it is possible to use Fire Walk to go through the first gate on the left.
Step One: stand in one of the cornerns of the gate and aim fire walk along the bottom of the gate until it clips through the gate.
If done correctly the player will clip through the gate and end up on the other side.
When on the other side the player can see floating buildings / parts of buildings.
On the right hand side the player can use Fire walk to move along the outside of the wall for a short distance.
p.s. it seems the fire walk trick can be done through most of the gates of this type on the map.