Darrell Bush, age 96, left, a former U.S. Army Staff Sgt. from Camp Springs, Md. and a WWII veteran of the Battle of the Bulge, arrives to place a flower during a centennial commemoration event at the Tomb of the Unknown Soldier in Arlington National Cemetery on Wednesday in Arlington, Va.

Darrell Bush, age 96, left, a former U.S. Army Staff Sgt. from Camp Springs, Md. and a WWII veteran of the Battle of the Bulge, arrives to place a flower during a centennial commemoration event at the Tomb of the Unknown Soldier in Arlington National Cemetery on Wednesday in Arlington, Va. / Pool/AFP via Getty Images

Since its creation in 1921, the Tomb of the Unknown Soldier has drawn crowds of tourists to Arlington National Cemetery to commemorate the unidentified service members who died in U.S. conflicts.

Members of the public don't typically get to walk directly on the tomb of the Unknown Soldier Plaza, however — that's a privilege reserved for sentinels of the 3rd U.S. Infantry Regiment, or The Old Guard.

But for the first time in nearly a century, visitors are allowed to walk on the plaza and lay flowers in front of the tomb as part of a two-day centennial event.

Stacy Wittmeyer kisses her daughter, Margaux Wittmeyer, 2, as her other daughter, Brynly Wittmeyer, 3, looks on after they and their family laid flowers at the Tomb of the Unknown Soldier during the centennial celebration.

Stacy Wittmeyer kisses her daughter, Margaux Wittmeyer, 2, as her other daughter, Brynly Wittmeyer, 3, looks on after they and their family laid flowers at the Tomb of the Unknown Soldier during the centennial celebration. / Tyrone Turner/ DCist/ WAMU

The Tomb of the Unknown Soldier Centennial Commemoration Public Flower Ceremony is free and open to the public on Tuesday and Wednesday, with registration required.

Visitors must have a government-issued ID and are encouraged to bring their own single-stem flowers, but the cemetery says it will distribute complimentary roses, gerbera daisies and sunflowers.

Additional rules and restrictions can be found here (no selfies, for example).

The cemetery explains that while ceremonies are held at the tomb almost every day, this particular commemoration was mandated in the 2017 National Defense Authorization Act. It will recognize the internment of the World War I Unknown Soldier and the dedication of the tomb exactly one hundred years ago, on Nov. 11, 1921.

Members of the Crow Nation, who had performed and laid flowers at the Tomb, exit the site.

Members of the Crow Nation, who had performed and laid flowers at the Tomb, exit the site. / Tyrone Turner/ DCist/ WAMU

And, officials added, it's not likely to happen again anytime soon.

"We do not anticipate holding another event in our lifetimes in which the public will be able to approach the Tomb in this manner," they said.

The cemetery will host additional events for Veterans Day on Thursday. These include a joint full honors procession and joint service flyover that members of the public can watch from a special procession route, as well as a Presidential Armed Forces Full Honor Wreath-Laying Ceremony at the tomb, which will be invitation-only because of the pandemic.

After placing flowers, a person in military uniform salutes at the Tomb of the Unknown Soldier.

After placing flowers, a person in military uniform salutes at the Tomb of the Unknown Soldier. / DCist/ WAMU

This story originally appeared on the Morning Edition live blog.

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Tags: Arlington National Cemetery  Veterans DAy  Tomb of the Unknown Solider