I cheated a little and got a head start by sketching the front of the Old Post Office last week (on a day that was much warmer and more suitable for outdoor sketching):

On the actual sketchcrawl day, I drew the statue of Benjamin Franklin, the first Postmaster General of the U.S., which stands in front of the Post Office:

The atrium contains a food court and shopping:

And from the observation tower you can get a nice view of the District:
