1. On December 5, 1791, the first ten amendments to the United States Constitution, known as the Bill of Rights, were added to the Constitution. These amendments protect the rights of individuals, including freedom of speech, religion, and the press, as well as the right to bear arms and a fair trial.

2. In 1835, the first mayor of Washington, D.C., William Winston Seaton, was inaugurated on December 5. Seaton was a prominent newspaper editor who helped establish the city's municipal government.

3. The Washington Monument in the National Mall was completed on December 5, 1884. It serves as a tribute to George Washington, the first President of the United States, and stands at 555 feet tall.

4. The National Museum of the American Indian opened its doors on December 5, 2004. The museum, located on the National Mall, features exhibits and collections dedicated to the history and culture of Native American peoples.

5. In 2013, same-sex marriage became legal in Washington, D.C., after the District's Marriage Equality Act was signed into law on December 5, 2009. The law allowed same-sex couples to obtain marriage licenses and legally wed in the District.