For the Seattle Public Library Koolhaas adopted several architectural styles. The exterior both encompasses futurism (clean lines, distorted shapes, advanced materials) and structural expressionism (detached frame and highly complex shapes requiring precision engineering). The outside of the building is made up of a diamond-shaped grid of steel and glass with an aluminum mesh supporting the glass panels. The interior - which is surrounded by the completely transparent glass skin - has the appearance of boxes moved around one position to stay within height and zone restrictions. This gives the building a complex polygonal shape. One example of how the design both creates an aesthetically pleasing quality and complies with the the city's zoning ordinances is where one side pulls back from the street to allow for a small recreation area.