There was controversy for a time for the distinction of what was then physically the largest high school in Maryland, between Northwestern and neighboring Montgomery Blair High School in Montgomery County. Both had been designed by the same architectural firm, around the same time (Blair in 1998; Northwestern in 2000); both share a similar design inside and out; and they are of similar size. Blair was constructed at originally and Northwestern at. Through certain technicalities, Blair's total square footage was upped to around . It was decided that Northwestern, with the addition of its greenhouse to the second floor of the A-Wing in 2001, retains its slightly larger physical size over Blair, despite Blair having a larger maximum student capacity.