DID I RUN THE LARGEST COMMUNITY CREATED MINECRAFT SERVER IN THE
  WORLD? I'm not sure, but if my math is right, Ken's Server* [
  [1]#Minecraft ] - which I've had off since September 2014 after
  23 months of almost non-stop operation ( the last few months
  were on and off though ) - all together was: 105222
  blocks/meters per side. 4278 square miles or 11081 square km [I
  left a few worlds out like the "Land of Ooo" and the Celestia
  MLP maps because we didn't all make those - I just downloaded
  them] which is almost as big as the real state of Connecticut,
  same size as Jamaica, and definitely bigger than Rhode Island
  and Delaware. It's also bigger than the "biggest server in the
  world" that's probably a lot prettier but heck, I didn't set out
  for pretty OR big.* I just wanted everybody to have a decent
  amount of real estate to work with. They're ONLY 84GB + 102000
  blocks across.* Beat ya and I WASN'T EVEN TRYING :P
  [2]http://www.vg247.com/2014/07/23/minecraft-largest-multiplayer-server/

References

  Visible links
  1. https://plus.google.com/s/%23Minecraft
  2. http://www.vg247.com/2014/07/23/minecraft-largest-multiplayer-server/