Element Labs, Inc. built this giant 45,000 square (!) feet LED display for the 2006 Asian Games ceremony in Doha, Qatar.
The massive size of the display—covering over 4,500 square meters, or 45,000 square feet—allowed it to be used in ways previously unachievable. ...
In keeping with the circular structure of the stadium, the screen was designed to be curved. The entire screen is 165 meters wide along the curve, reaching 39 meters at its highest point. The screen is comprised of 20,000 individual Versa RAYs, which laid end to end would span 58 kilometers (over 36 miles). 762,000 individual LEDs were used, with a pixel pitch of 77 millimeters.
Link (with lots of cool pics) - Thanks Jason Mika!
1 square meter = 10.76 square feet (since it's 3.28 x 3.28)