Centre piece is a cherry tree, which extends through the floor and emerges as the newel post above. The steel support work was custom fabricated, the mahogany handrail was fabricated in place. The stair treads are custom made of spalted white birch, all cut from the same log. The log was cut into 2″ thick elliptical slabs, at about a 70 degree angle to the bole. Note the radial grain pattern on each tread. Via legerdemaine’s photostream on Flickr