The Mannesmann Giant Triplane was found in an incomplete state, in a hangar on the airfield at Poll, near Cologne, by an Inter-Allied Aeronautical Control Commission team in 19196.
Initially thought to be a giant bomber capable of bombing New York, it is now thought to be a trans-atlantic ranged transport aircraft.
Designed by Villehad Forssman, designer of the SSW R-plane, the aircraft was initially financed by the Deutche Bank, and Bruning & Sohn A.G.,
"owners of the four largest high quality plywood factories in Germany." Unsurprisingly, plywood was used extensively in it's construction.
Missing several components when found, leading to the conclusion that these were constructed elsewhere, the I.A.A.C.C. team were impressed both with the overall concept, and detailed construction work they found, but were sceptical of the overall structural concept, considering it overweight, but at the same time weak.
It has also been reported that the Triplane's mission was to drop propaganda leaflets over the USA, before that country entered the war.
Illustrated below, a provisional 3-view of the aircraft, and a view of the interior of the fuselage.
Sources :- Putnam's 'German Giants', pp.152-6, 'Giants of the Sky', Gunston, page 38.