The Antinov AN-225 is still the world's largest airplane. Here's an interesting article I found:
http://www.aerospaceweb.org/question/design/q0188.shtml
I believe there are a total of 2 built, and only 1 still are able to fly-the other is dissassembled, and used for parts. It was originally used to haul the russian's space shuttle around, similar to our modified 747 does. But, at the fall of the soviet union, the plane was scrapped. It was brought back up, and put together, and is used for hauling large cargo loads-more then it's smaller sister plane the 124.
Pic:
Note: size of people at the bottom. That's a fuckin plane.
-A. Swift