Bronze, granite, and water will all play a role at the 9/11 Memorial. In this short video, the memorial's architect and designer, Michael Arad, examines a small mock-up that has been assembled at the Brooklyn Navy Yard to see how the materials interact, how they hold up to the elements, and what the finished memorial will look like to visitors.

NOVA is produced by WGBH in Boston. Funding for NOVA is provided by David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and PBS viewers.