Constitution Avenue is one of DC's main arteries because along it is access to the Washington Monument, the Capitol building, many government buildings, much of the Smithsonian Museums, and the Mall. It's easy to travel because it's 3 lanes wide in each direction and many of the lights are synchronized. You can also park along the street and a space is not all that hard to find. It's easy to access to as it is right of I-66 for Virginia travelers.