1. The Boston Tea Party occurred on December 15, 1773. This event was a crucial moment in the American Revolution and helped catalyze the movement for independence from Great Britain.

2. On December 15, 1791, the Bill of Rights was ratified by the Commonwealth of Massachusetts. This document guarantees individual freedoms such as freedom of speech, religion, and press, as well as the right to bear arms.

3. The first public high school in America, the English Classical School, opened its doors on December 15, 1821, in Boston. This school aimed to provide a classical education to all students, regardless of their socioeconomic status.

4. On December 15, 1836, the Great Fire of Boston destroyed much of the city's downtown area. The fire burned for over 12 hours and destroyed over 600 buildings, leaving thousands homeless.

5. Massachusetts became the first state in the nation to legalize same-sex marriage on December 15, 2003. This landmark decision was a major victory for the LGBTQ+ community and helped pave the way for marriage equality across the United States.