This refurbished duplex in Amsterdam, designed by MAMM Design architects, is like a modern treehouse fit for kids and adults alike. Designed with layers of right angles, the light seems to bounce off the white walls and natural materials such as burlap, glass and medium tone woods. The highlight is the sunken kitchen in the heart of the open concept living area. The low-hanging bar is not only whimsical — it might just be the right height for their little tots.