WeLoveDC dusts off widely held myths about DC and debunks them:

http://www.welovedc.com/2009/07/07/dc-mythbusting-built-on-a-swamp/

...was DC really built on a swamp? Not really– today it’d be called more of a tidal plain. When Pierre L’Enfant set out with a team to survey the city, there was a lot of variety in what he found: fields of tobacco and corn, small forests, and some waterside bluffs and wetlands.

More good reading at http://www.washingtonpost.com/wp-srv/artsandliving/magazine/features/200...