Exterior and Concrete Siding Material The new concrete exterior has already been transformed by the rain and humidity of the Azores, and now sports an aged look. The color contrasts with the basalt wall and dark soil of the Ilha Preta ("Black Island"). Vieira da Silva anticipates that surprising patterns and textures will develop on the outer walls over time.  This Modern Coastal Escape Sits Within 18th-Century Stone Walls by Patrick Sisson