The National September 11 Memorial Museum opens to the public today.

Red Cross counseling volunteers will be on hand to help people cope with some of the more difficult to watch videos and images of the Twin Towers collapsing on that fateful day.

One designer who helped create the exhibits says "there's a lot of thought given to the psychological safety of visitors."

There are built-in tissue boxes and a layout designed to let people bypass the most intense exhibits if they choose. Discreet oak-leaf symbols denote items connected to the dead, and images of falling victims are in an alcove with a warning sign.