Yes, that’s the Post Office. It hasn’t been used for retail operations for some time (the one further west on Rte 7 replaced it, with a much smaller footprint). The City’s planning website has the development details, including a traffic impact study which proposes changing the traffic light frequency to accommodate more cars.
As a side note, a NoVa transportation organization (forget the name) recently secured $100K in federal funding to study the traffic on Rte 7 from Alexandria to Fairfax and propose changes.
Seems to me like we could save a gazillion dollars if the government would quit paying out so much money on studies. Roads have maximum capacities like everything else in life. You can’t put three pounds of s**t in a bag designed to hold two pounds, doesn’t matter what you do to it or how much money you spend studying it.
I sometimes take Rte 7 from FC to Alex ... it is lengthy but sometimes faster than taking 66/110. Tho I often cheat and cut down Seminary.
The day I moved to DC, I drove Rte 7 from a then-newly opened stretch of Beltway to 7 Corners. There were only horse farms @ Tysons Corner; 7 Corners Center was the place for upscale shopping: Garfinckel’s/Woodies/Lord & Taylor. Times have sure changed.