Step 1 : Introduction to the question "Which monumental obelisk is the tallest structure in Washington D.C.?"
...The tallest structure in the capital city of Washington, D.C., excluding radio towers, is the Washington Monument, which rises 555 feet and was completed in 1884. Built to honor George Washington, the first President of the United States, the Washington Monument was once the tallest building in the world at just over 555 feet. The monument to America’s first president still holds the title of world’s tallest stone structure and obelisk. The Washington Monument is currently closed until spring 2019 for repairs that will modernize the elevator and increase long-term reliability and safety.