You may have heard that, by law, the Washington Monument is the tallest structure in DC. I'd heard this too. But it turns out that that's only somewhat true.
Urban Planet gives the rundown. Basically, DC used to have a height ordinance that made the Capitol the tallest building in town. While that is no longer in effect, current law says that new buildings can be no more than 20 feet taller than the width of the street in front of it. And this effectively preserves the Monument as the tallest structure in DC, and gives the city a different look than most American metropolises.
I wish I had a screenshot to show how well JLU actually captured the appearance of the National Mall in its four seconds onscreen. Pennsylvania and Maryland Avenues are prominent, as are the Smithsonian buildings. On the other hand, it looks like the Cadmus building is smack dab in the middle of the Potomac River, or possibly inside Arlington National Cemetery.