Stairwell in the Department of Philosophy building of New York University, New York City

© Alex Fradkin/Gallery Stock

Stairwell in the Department of Philosophy building of New York University, New York City

A skylight at the top of the stairwell of the six-floor philosophy building for New York University lets in more natural light. And the windows on the top level are covered in prismatic plastic, so when the sun is in the right position, mini rainbows climb across the walls of the stairwell. The design, by American architect Steven Holl, is part of a major remodel to the space that was completed in 2007.