The Associated Press reports that a "basketball-sized piece of marble moulding fell from the facade over the entrance to the Supreme Court, landing on the steps near visitors waiting to enter the building.":

  The marble was part of the dentil moulding that serves as a frame for the frieze of statues atop the court's main entrance.
  A group of visitors had just entered the building and had passed under the frieze when the stone fell at 9:30 a.m. ET.
  Jonathan Fink, a government attorney waiting in line to attend arguments, said, "All of a sudden, these blocks started falling. It was like a thud, thud."

  Maybe it's another trick they play on all the new Chief Justices. Thanks to Daniel Solove for the link.