A village of beautifully designed, sustainable modular treehouses lining the grounds outside of a 13th century French castle may sound like the stuff of dreams. But Mexico-based architectural firm Forma Atelier is determined to make it a reality. The company created the project as an entry for the Tree House Module competition organized by French company Dartagnans. Designs for the treehouses feature simple fabrications and the use of materials like steel, wood and glass, chosen not only for their sustainable elements but also for their simple, uncomplicated construction.