Selfies in front of the Smithsonian Castle are a must but don't forget to peak at the extensive gardens in the back.
These gardens are right next to the reflecting pool but you might miss it on the way to the Lincoln Memorial. Check out the Founding Fathers' signatures carved in stone.
You might miss the FDR Memorial if you don't walk around the Tidal Basin. Walk through all four of FDR's Presidential Terms and enjoy the cascading waters.
Keep walking around the Tidal Basin to find this memorial. Mason authored of the Virginia Declaration of Rights that inspired the United States Bill of Rights.
If you are museum and monument focused, you might miss the Sculpture Garden outside the National Gallery of Art - the perfect spot to stop for a picnic or to buy food.
Across the Mall, enjoy another sculpture garden outside the Hirshhorn Museum filling with winding paths and reflecting pools.