Towering 85 meters above the Norwegian countryside, Mjøstårnet is the world’s tallest wooden building, made almost entirely from the trees of neighboring forests. But as recently as the end of the 20th century, engineers thought it was impossible to build a wooden building over 6 stories tall. So how do wooden structures like this compare to steel and concrete skyscrapers? Stefan Al investigates. Lesson by Stefan Al, directed by Franz Palomares.