The Nazi-funded Hindenburg airship was as big as the Titanic and was one of the great engineering feats and mechanical sights of the early 20th century.
But on Thursday 6 May 1937 disaster struck, when it caught fire and was destroyed as it tried to dock with its mooring mast at the Lakehurst Naval Air Station in New Jersey. Of the 97 people on board, 35 were killed.
As the first major transport disaster captured on film, it was the subject of spectacular newsreel coverage, photographs and Herbert Morrison's recorded radio eyewitness report from the landing field, which was broadcast the next day.
The crash left such an impression on the world that it ultimately led to the end of the golden age of airship travel.
Dozens of theories exist about why the Hindenburg went down: was it a static electric charge or a fundamental flaw in its design? Or could it have been an act of sabotage with a bomb?
Because of the sheer size of the Hindenburg and the intricacies of its design, three quarters of a century later no one has been able to provide a satisfactory explanation for the disaster.
Now, in the most ambitious testing programme ever undertaken, a team of experts including aeronautical engineer Jem Stansfield build three scale models of the Hindenburg and, for the first time, put the leading theories to the test in the field to establish which was most likely to have caused the crash.
And, speaking for the first time on television, an eyewitness sheds fresh light on the cause of the disaster.