Mourners filed quietly past the late Supreme Court Justice Ruth Bader Ginsburg's flag-draped coffin outside the white marble court building on Wednesday as the United States began three days of tributes to the liberal icon.

Hundreds of people lined up outside the court for a chance to pay their respects to the pioneering women's rights advocate, who died on Friday at age 87. Inside the court, Ginsburg's fellow justices celebrated her life in a private ceremony.

"Her voice in court and in our conference room was soft. But when she spoke, people listened," Chief Justice John Roberts said.

Ginsburg's casket was then moved under the neoclassical court building's massive Corinthian columns for a public viewing due to last two days.