The crown jewel of Grand Central, this Main Concourse landmark has everyone saying, “meet me at the clock!” There, you will find a window where over 1000 questions per day are answered. The clock—like all clocks in the Terminal—is set by the atomic clock in the U.S. Naval Observatory in Bethesda, Maryland, and is accurate to within 1 second every 20 billion years! This famed opal glass clock above the Information Booth is valued at as much as $20 million.