Things to do
The National Arboretum is a dream background for your fall photos. There are so many gardens and trails that it never feels overly crowded.
Malcolm X Park is under some construction right now but you can find lots of trees and benches on the upper deck. This is also my favorite fall spot after a light rain.
Rock Creek Park has lots of trails, streams, and picnic areas to enjoy the fall leaves. Wait until the leaves start to fall to have lots of space to step through crunchy piles.
Roosevelt Island can get busy on the weekends so try to visit during the week or take ride share to avoid parking issues. Check out the monuments and explore the trails.
Explore the foliage on your trip to Mount Vernon. Plus, look out for special events like whiskey tastings, The Fall Wine Festival, Fall Harvest Festival, and Trick-or-Treat.