A wreath-laying ceremony is being held in the US city of Arlington at the Arlington National Cemetery on Thursday to commemorate the 100th anniversary of the monument, along with National Veterans Day.
The occasion is expected to be marked with a joint service flyover and full honours procession. An Observance Ceremony at the Arlington National Cemetery's Memorial Amphitheatre is to follow.
The Tomb of the Unknown Soldier was initially dedicated on 11 November 1921, when an unknown World War I soldier was buried at the Arlington National Cemetery. Over the past century, more unknowns were buried at the tomb.
Follow Sputnik's live feed to find out more.