What are the top 5 things people don't know about Washington DC?

[Carl_Beck]

Pure honesty wins.

[Michael_Blow]

1. Almost all museums and other attractions are free.
2. There are no skyscrapers due to a height restriction on buildings (about 13-15 stories max).
3. Washington and DC are not the same thing. Washington = the government. DC or the District = the city. We have to pay all the same taxes as any other US citizen but have no votes in Congress.
4. If you're on the left side of an escalator and standing still, you're getting knocked down. Walk left, stand right.
5. We drink more wine per person than anywhere else in the US.

[Ariana_Thompson]

Just three things from me:

DC is one of the more violent places to live, ranked only a few behind Baltimore. http://www.worldatlas.com/articles/most-dangerous-cities-in-the-united-states.html

Parking in DC with a car is a nightmare. The signs are confusing and most tourists will get a ticket.

You can walk into the embassy (usually without an appointment) to obtain a travel visa on short notice if you go early enough.

[Matt_Camp]

1. The Library of Congress is a stunning building and a great museum on par with the better known Smithsonian Institutions. Go check out a copy of the Gutenberg bible.
2. Streets are named in a grid system with letters of the alphabet, however there are no J,X,Y and Z streets.
3. The Lincoln Memorial is open late at night, including the little museum beneath the stairs.
4. The National Gallery of Art has the only DaVinci panel painting in the Western Hemisphere.
5. It's becoming a foodie city.

[mastigosatlarge]

Only one to add--if you're on an escalator, like in the Metro, stand on the right, walk up or down on the left. If you stand on the left, you'll be called an "escaleftor", and people will literally shove past you.

[Tiffany_Hrbacek]

Some more practical and less touristy things include:
1. Don't drink DC tap water (Northern Virginia water is usually safe)
2. It's fast paced. People speak quickly and have relatively small amounts of patience when it comes to waiting for service, in lines, on escalators as others mentioned, in traffic, for pedestrians to cross, etc.
3. There are a lot of big egos here, but don't take it personally. You'll especially encounter it when driving: people can't let others merge in front of them, there is tons of tailgating and, let's say "angry" passing, and overall lots of road rage here.
4. Speaking of driving, people completely forget how to drive when the weather changes (e.g. the sun comes out, it's cloudy, it rains, there's snow), which causes a ton of unusual traffic and accidents.
5. The whole area can't cope with even the slightest amount of snow, which is good for getting off of work/school!

[Tiffany_Hrbacek]

One more thing: Public transportation will get you there...eventually. Although there are a lot of metro, train, and bus stops and lines, they really are not the most reliable. So if you're going somewhere, make sure you plan for the inevitable delays and the occasional completely missing busses or trains.