A little help in visualising an early scene in The Lost Symbol: here's the rotunda of the U.S. Capitol in all its glory. The photo was taken during a memorial service for former President Gerald Ford in 2006 (and is in the public domain). Click for a huge version (2000px by 3000px):

Though it hardly needs pointing out, Brumidi's Apotheosis of Washington dominates the upper half of the image. Awe-inspiring setting really.