On 9th June 2006, Reinhold Messner opened his “Messner Mountain Museum” at Castel Firmiano near Bolzano. The film chronicles the birth of the mountain museum: from the harsh controversy on the project, the construction, the architectural solutions presented by Werner Tscholl and the interior decoration designed by Reinhold Messner himself. “If I do something, I do it with all my heart” says the climber to the interviewer. And this is what we see in the film: Messner who carries boxes, takes measurements, moves stones, hangs paintings and positions statues. The film Der 15. Achttausender chronicles day by day the birth of the museum. Messner talks about the philosophy and ideas behind his project. The film not only shows backstage at the “Messner Mountain Museum”, but also takes the audience into Reinhold Messner’s fascinating way of thinking.