For decades, Rosslyn has had the tallest buildings in the Washington region. But they're still not that tall — they max out at around 400 feet, which is well below the height of the tallest buildings in most major US cities. So why doesn't Rosslyn have bigger buildings?
The flight path for planes taking off and landing at National Airport passes over the Potomac River, and is pretty much right on top of Rosslyn. Of course, nobody wants a plane to crash into a building.
You can see the close relationship between the buildings and the flight paths in this photo, which was taken from the National Cathedral observation tower. A plane heading to DCA flies over Rosslyn at only a few times the elevation of the buildings. If the buildings were any taller, the threat of a collision would be too high.