Set on the serene Tidal Basin, the Thomas Jefferson Memorial is a must-see, especially if you can time your visit with the cherry blossoms in spring for some truly spectacular views. It’s a peaceful spot to reflect, with inspiring quotes from Jefferson etched into the grand, Pantheon-style walls. You can easily spend an hour just taking in the architecture and the stunning panorama of the Washington Monument across the water. It's open 24/7 and is a beautiful sight both day and night.