According to the History.com, the Washington Monument in Washington, D.C., was built to commemorate George Washington, the first president of the United States. The 50 flags surrounding the base represent the 50 states.
The original plan for the monument, in 1783, was to build a statue of Washington, who served as the commander-in-chief during the American Revolutionary war. This plan was established before Washington became president. After Washington died, Robert Mills won the design competition for his memorial. His design included a pantheon with many columns and many statues inside. The construction was held up for many years before the monument that stands today was finished in 1884. The monument is approximately 555 feet tall and was opened to the public in 1885.