1. Building the Capitol: On December 15, 1791, the cornerstone was laid for the new United States Capitol Building. The building was designed by William Thornton and the project took nearly 34 years to complete.

2. The Washington Monument: The Washington Monument in Washington, D.C., was completed on December 15, 1884, and is the tallest stone structure in the world, towering at 555 feet.

3. The Pentagon: On December 15, 1941, ground was broken for the construction of the Pentagon in Arlington, Virginia. The building was designed to be the global headquarters of the U.S. Department of Defense.

4. Bill of Rights Ratified: On December 15, 1791, the Bill of Rights was ratified by the required three-quarters of the states. The Bill of Rights consists of the first ten amendments to the United States Constitution, ensuring citizens' basic rights and freedoms.

5. MLK Memorial Dedicated: On December 15, 2011, a memorial to civil rights icon Martin Luther King Jr. was dedicated on the National Mall in Washington, D.C. The statue stands 30 feet tall and depicts King emerging from a stone of hope.