Grand Central Station is not only the name of the Post Office next door, but also the name of the old train station that sat on the site of where the current Grand Central Terminal sits now. The current station was built atop of the old site, renamed, and reopened to the public in 1913.
This vintage photograph shows the West Balcony in the famous Main Concourse as it appeared around 1915. Notice the Baggage Room on the far end, since replaced by a matching staircase in a mirror image of the West Stairs.
Check out the specimen page on the Library of Congress for more info on the photograph.