Out East we have 'the Mill' which is basically an abandoned paper mill. It's VERY big. I'd be curious to know what the square footage is. There's 2 stories of offices, and 2 other floors of very large rooms and off to one side is a paintball area. It's about 200 meters x 150 meters for 2 floors + basement (not used) and about 80 metres x 150 metres for the top 2 floors which is the office space.
Here's some pics :http://www.pbase.com/chef40/cure&page=all
And video :
"You want to talk to God ? Let's go see him together, I haven't got anything better to do."