Lincoln Memorial's hidden 15,000-square-foot undercroft opens to the public after a century underground

Now, a glass-encased exhibit area floats within the infrastructure beneath the statue of the 16th president.

The highly anticipated museum features interactive physical displays, multimedia video presentations and a bookstore.

Visitors will also get a unique glimpse into the memorial's construction, featuring historical tools and authentic graffiti left behind by original workers in the 1920s.

Beyond its physical foundations, Moore said, the undercroft tells the story of how the Lincoln Memorial evolved into America's "civic stage."