The biggest bombs available before the nuke, were the ten tonne "Grand Slam" bombs. This video shows how massive they were, and what they could do upon impacting the ground. Pretty cool! Enjoy!

The Atomic Cannon detonated at the Nevada Test Site in 1953, showing the atom bomb detonation and weapon effects. It exploded with a force of 15 kilotons. At this force it is actually called a tactical atomic bomb. This video sequence is from "Trinity and Beyond - The Atomic Bomb Movie"