Main Concourse's clock, Grand Central Terminal

The Main Concourse is the primary concourse of Grand Central Terminal, a railway station in Midtown Manhattan, New York City. The space is located at the center of the terminal's station building.

The clock was designed by Henry Edward Bedford and cast in Waterbury, Connecticut.[5] Its mechanism was designed by the Self Winding Clock Company and built by the Seth Thomas Clock Company, along with several other clocks in the terminal. Each 24-inch (61 cm) face is made from opalescent glass, now often called opal glass or milk glass. An urban legend, which arose in news reports in the 1990s or even earlier, claimed that the clock faces were actually made of opal, a precious gem, and that renowned auction houses had estimated their worth at millions of dollars. This myth was spread by tour guides in the terminal, by its presentation as fact in Wikipedia from 2006 to 2013, and by major news publications into the present day. It was debunked by Untapped New York in 2020.