The Breguet Br.460 Vultur was a French bomber developed in the 1930s for the French and Spanish Republican air forces.
Witteman-Lewis XNBL-1 strategic bomber - photo and video
Vickers Wellington bomber - photos
Handley Page Heyford bomber - photos
C-87 Liberator being assembled in 1942 - photo
Douglas XB-19 under construction - photo and video