1. In 1865, the US House of Representatives passed the 13th Amendment to the Constitution, abolishing slavery throughout the United States. This amendment was first introduced by Representative James M. Ashley of Ohio in January 1864 and was eventually ratified by the required number of states on December 6, 1865.

2. In 1929, the St. Elizabeths Hospital in Washington, D.C. was officially opened. This psychiatric hospital was established by Congress in 1852 and became a renowned center for the treatment and study of mental illness. Among its patients were poet Ezra Pound, civil rights activist Stokely Carmichael, and John Hinckley Jr., who attempted to assassinate President Ronald Reagan in 1981.

3. On January 31, 1944, a fire broke out in the U.S. Patent Office Building in Washington, D.C. This massive blaze destroyed more than 400,000 patent models and 2 million signatures of original patent documents. The cause of the fire was never determined, but it resulted in major changes to the patent application process and the creation of the Patent Office's fireproof National Archives building.

4. In 1950, President Harry S. Truman signed Executive Order 10030, authorizing the building of the Pentagon in Arlington, Virginia. The world's largest office building was constructed in just 16 months and served as the headquarters of the Department of Defense until the opening of the new Pentagon building in 2011.

5. On this day in 2010, District of Columbia Mayor Adrian Fenty signed the Religious Freedom and Civil Marriage Equality Amendment Act, legalizing same-sex marriage in the nation's capital. The bill had been previously passed by the City Council, but faced opposition from some religious groups and conservative politicians. Despite controversy, the bill was enacted and marked a significant milestone in the fight for LGBTQ rights in the United States.