For the longest time, the Philippine record (at least in my books) for the largets Dropdown Banner cum billboard has always been the Coke execution on Regalla Towers, Cubao in May 2001. Executed by DDBS Advertising, the Coke execution measured 70 feet wide by 140 feet tall.
Just this week, Carranz Outdoor beat that record with an execution for Nike entitled "RUN ON AIR", placed at the south wall of the newly constructed GA Tower on EDSA-Boni Avenue.
I still have to get the specs for this but as it is, the banner is really an awesome site. Credit goes to Mindshare for pulling off this execution.