This question comes up quite a bit! But I can't remember the answer. However, one idea you can always do is use the Game Finder to find the older 'active' games, and take a look at them.
A quick game finder search shows a plethora of games into 200, 300, 400, 500+ rounds. And a few higher, like:
Game 578682. It is on Round 3283. And the game was started on: 2007-07-03 11:58:07 - Game has been initialized
--Andy