Items in this area:
Ether
Examine the box-shaped object in the lower right to try and start a
nearby propeller. Head up, and you'll jump onto the propeller. From
there, make your way to the other box and activate the painted barrier.
Climb up it, and use the O button to jump onto the swinging metal pipe.
After that, climb up to the next screen.
Once here, climb up, then drop down to activate the next box and you'll
find an Ether. Climb down the lefthand pipe and make your way back up
again. Instead of dropping down, continue up, and you'll find yourself
at Shin-Ra's headquarters.