The Grand Central Terminal Clock, the most iconic feature of Grand Central Terminal, is a four-faced brass clock on top of the central information booth. The clock was designed by Henry Bedford for the Connecticut clock crafting company Seth Thomas. The clock was completed in 1913 to honor the opening of the Grand Central Terminal. The clock also happened to be completed the same year as the 100th birthday of the Seth Thomas Company.
Each of the four clock faces is made from opalescent glass (now often called opal glass or milk glass) though urban legend misconstrues this fact and claims that the faces are mistakingly made of “opal”. The clock is valued in the tens of millions of dollars.
The clock is set every second by the atomic clock in Naval Observatory in Bethesda, Maryland. This means that the clock is accurate to within one second every 1,400,000 years.
The large American flag behind the clock was hung a few days after the September 11th attacks on the World Trade Center.