Russia's K-7 Flying Fortress: A new meaning to the word "gargantuan".
The weaponry carried by this behemoth is shown in the last two pics!
(The K-7 first flew on 11 August 1933)
In 1930s the Russian army was obsessed with the idea of creating huge planes. At that time, they were proposed to have as many propellers as possible to help carry those huge flying fortresses into the air. Jet propulsion has not been implemented yet.