Dornier Do-X was produced in Germany in 1929 as the largest flying boat in the world. It was constructing by Claudius Dornier during nine years and originalyy was intended for trans-atlantic voyages. Twelve engines at 610 hp each lift the aircraft at altitude of 500 meters and allow carry from 66 to 100 passengers (depend on distance of flights), although during test flight Do-X get on board 169 people, including crew of 10 men. It was world recorord, that was beaten only 50 years after. Transatlantic test flight lasted over year. England, Netherlands, France, Spain, Portugal were visited during the flight before Do-X finally reached New York, where the palne and crew spent nine month. Being part of Lufthansa, Do-X undertook numerous flights to Vienna, Budapest, Istanbul before it became the centerpiece of Berlin aviation museum in 1934. It remained the main exhibit almost next 10 years, until it was destroyed during allied air raid in November 1943.
Aside original German Do-X there were another two, built in Italy in 1931 and 1932. These X2 and X3 were used for transport flights, including military purposes like transporting troops to Ethiopia in 1935. None of them were survived after WWII.