In the early days, though hundreds of Confederate soldiers were buried at Arlington, it was considered a Union cemetery and family members of Confederate soldiers buried there were not allowed to visit the graves.
In 1900, Congress authorized a special section of Arlington to be set aside as a burial location for nearly 500 Confederate soldiers. They are buried in concentric circles, with the monument built in the center.
On June 4, 1914, President Woodrow Wilson spoke at the monument as veterans from the Union and Confederate Armies laid wreaths on the graves, as a symbol of unity.
Since then, American presidents have sent a wreath to adorn the monument. President George H.W. Bush changed the tradition by sending a wreath on Memorial Day, not on Davis' birthday as his predecessors had done.
President Obama used his weekly radio/Internet address to pay tribute to America's veterans, servicemen and women, and their families.
"This is not only a time for celebration, it is also a time to reflect on what this holiday is all about; to pay tribute to our fallen heroes; and to remember the servicemen and women who cannot be with us this year because they are standing post far from home – in Iraq, Afghanistan, and around the world," he said on Saturday.
ABC News' Sunlen Miller contributed to this report.