Originally Posted by galexander
Get real EireEngineer.
Looking from directly over-head you get exactly the same impression. Unfortunately I couldn't immediately find such an image on the internet.
Anyway you can see it quite clearly from an angle as well.
Then you must truely suck at using google. It took me all of five seconds to find a overhead view, and i will concede the point that it is a very rounded square. However, you have to realize that the impact is not the only force at work there. The sides of the crater have erroded and collapsed over time, giving it a slightly more square shape.