Lots of buildings have green roofs covered in vegetation and soil, but this building design from Graft Architects is the first I’ve seen that has a green hill. The apartment complex, constrained by restrictions in height and width, features a “living hill” on its roof that drapes down the sides of the building. Balconies are cut into the roof to provide a view of the city below. Graft’s project is set to be completed in 2012 in an undisclosed location in Japan. No word yet from the architecture firm on whether the building’s owners will lead hikes up the rooftop hill.