Bolide sites?

[Dan Tapster <dan.tapster@bbc.co.uk>]

I am still getting replies as to the causes of the K/T mass extinction.
Again most people seem to be in favour of the asteroid exacerbating the
dinosaurs' decline.

I was wondering if anyone could recommend the most spectacular asteroid
crater site (although not from the K/T obviously).   The bigger in
circumference and depth,  the better. It would also be good if these sites
were convenient to reach!

Thanks,

Dan Tapster