The Memorial Museum dedicated to the victims of the Sept. 11 terrorist attacks will be open to the public at the World Trade Center site on May 21, officials said Monday. The opening will follow a May 15 ceremony and a six-day dedication period, said Joe Daniels, president of the National 9/ 11 Memorial and Museum. During the tribute-filled dedication period, the museum will remain open 24 hours for 9/11 families, rescue and recovery workers, survivors and lower Manhattan residents and business owners. The museum includes two core exhibitions at the foundation, or bedrock, of the historic trade center complex. One of the exhibitions, called "In Memoriam", pays tribute to the 2,983 men, women and children killed on 9/11 and in the Feb. 26, 1993 bombing of the World Trade Center. The other tells the story of what happened on Sept. 11 at the three attack sites and around the world. It also explores what has led up to the terror strikes and shows how the incidents continue to shape the world. The history is told through monumental and personal artifacts, photographs, audio and video footage, first-person testimonials, and personal possessions and memorabilia. "Building the museum is in large part the answer to the violence of the 9/11 attacks. The stories of heroism, of valor and the unwavering spirit felt and witnessed on that day, and the ensuing months, will be told for years to come after the Museum's doors open to visitors from around the world," said Michael Bloomberg, the 9/11 Memorial Chair.