Does it still wave?
My country's national anthem was written on this day in 1812 by Francis Scott Key. The anthem itself wasn't recognized as the US national anthem until over 100 years later, when ordered so by Congress in 1931. The original 15-star flag that inspired Key to write the verses still exists, and is held in the Smithsonian.
Here's a fact about the Star Spangled Banner that I recently realized: The first stanza of the song is the only part that you typically hear performed. In the first stanza, there are more questions than real answers. For example, the chorus: