 One of the top viewed videos over on Google is this video of a nuclear bomb test from 1953. The yield of the bomb was about the same as the one used over Hiroshima, Japan. It appears to be an underground test as I don't see a shockwave at all or if there is one it doesn't pass over the camera (like the one which sweeps over the ships in the South Pacific test videos if you've seen them). The mushroom cloud just keeps rising and rising off this thing. You can probably use Google Maps to see the crator from this test.
Watch the full video of a nuclear test from 1953 below or click over and view it on the host site. Source: Google Video | 
