From about 1909-1918, Fort Lee was the film capital of the United States. Hollywood opened a film studio in 1911 but it wasn't until the early 1920s that the West Coast become the film capital it is now.
At the posted coordinates, you will find the first sign about Fort Lee's Film History. This one will be about American Eclair Studios. The last sentence talks about abandonment and gives a year. Remember this year (ABCD).
Keep walking to the second sign about a Fire at the National Evans Film Laboratory. Take notice of the age of the fireman at death (XY).
The final coordinates are:
N40 51.(A+C)(A+C)(C+C)
W73 58.(X)(X-X)(Y-X)