Naturschutzbund, the Austrian Nature and Biodiversity Conservation Union, asked Loenhart and his partner, Christoph Mayr, to create a place from which to observe the ecological restoration of the river, once part of the Iron Curtain and now in the European Green Belt. The architects didn’t want to interrupt the flow of the pathway through the woods. After climbing the tower’s 168 steps, visitors descend a second, intertwined staircase. Steel girder joints connect welded steel pipes in the double-helix structure. The pipes decrease in diameter toward the top of the tower,like the branching pattern of a tree. The architects were inspired by the flights of steps leading to a 1499 castle in nearby Graz.