The Sears tower has added retractable compartments on the 103rd Floor. Yeah I know I once stood in the frame of Windows on the World for a better view but this thing would give me the mother of all panic attacks.
http://www.towleroad.com/2009/07/sears-towers-ledge-not-for-those-with-vertigo.html
Houndentenor
"Get the trash off the street and back on the stage where it belongs." -- Bette Midler