9/11 Memorial Museum Photo: AFP

On May 21, when the doors to the 9/11 Memorial Museum open for the first time, visitors will pay solemn tribute to the thousands of victims who died in the terrorist attacks, retrace the events leading up to the fateful day and examine how the tragedy continues to shape the course of the world today.

Before it opens to the public, however, the museum announced this week that it will be holding a special dedication period reserved for 9/11 families, rescue and recovery workers, active duty first responders, survivors as well as lower Manhattan residents and business owners.

Between May 15 and May 20, the museum will be open 24 hours a day as a tribute to the thousands of rescue and recovery workers who worked around the clock in the aftermath of 9/11.

The day after the dedication period ends, the museum - located at the site of the former World Trade Center - will open to the general public and tell the story of 9/11 through multimedia displays, archives, narratives, and artifacts displayed across 110,00 square feet (10,219 square meters).

"The 9/11 Memorial Museum is for all of us," said Mayor Bill de Blasio in a statement.

"It is for those of us who witnessed the events, either with our own eyes or on TV, and are still struggling to make sense of it. It is for future generations who will first encounter 9/11 as history, but who must come to understand it as something real and terrible, something that must never happen again.

"But most of all, it is for the survivors, the families, the rescue and recovery workers, the first responders.

"We thank them for sharing the stories with the world, so that we may learn from them."

The exhibit will be divided into two parts: "In Memoriam" will pay tribute to the 2,983 victims killed in the attacks of September 11, 2001 as well as the 1993 bombing of the World Trade Center on February 26.

The historical exhibition will retrace the events leading up to the attack, revisit the three attack sites, and examine how 9/11 has changed the course of history.

The museum exterior, designed by Michael Arad and Peter Walker, consists of two reflecting pools formed in the footprints of the original Twin Towers.

Tickets for the general public will be made available March 26. Though admission is free, passes must be reserved. A $2 fee is applied for reservations made by phone or online.