Wolfgang Bankstahl of Multilayerladen, Berlin (Markthalle IX) What: A proposal that puts public parks on top of stepped buildings. Description: Look down on these densely packed buildings and you’ll only see green. Designer Bankstahl makes double use of the space, putting homes and offices inside while letting people climb onto the lush, landscaped roofs. Why: A compromise between public and private needs. The scheme gives developers maximum income from the land but also expects them to pick up the tab for the parks. Why not: Will tenants be happy with 24-hour foot traffic over their heads?