For those trying to visualize Dan Brown's route around Washington, D.C. in The Lost Symbol, here's a handy little map to show you where everything is at a glance. Click for a larger version (approx. 500kb):

Due to the scale of the map, a few of the less important landmarks aren't included. Perhaps might be worth assembling a set of Google Earth/Maps co-ordinates as well for those that want to fly about the city - feel free to post any location co-ordinates you may have yourself.