The Washington Monument is a massive obelisk on the National Mall built to commemorate the life of George Washington, the first president of the United States. It is recognized as the world’s tallest stone structure, and is the tallest structure in Washington D.C. The monument is an iconic image of America, let alone D.C., and one would have to really try to miss it on a visit. Relatively unknown is that the monument has an enclosed observation deck at its top that is open for visits at no cost. Book a time slot and make sure to be ready when the elevator opens.