1. On March 15, 1769, the Spanish explorer Gaspar de Portolá and his expedition party were the first Europeans to come across the San Francisco Bay. They named the body of water Bahía de Nuestra Señora de la Merced de los Buenos Aires, and it would later become the site of the city of San Francisco.

2. March 15, 1848, marked the beginning of the California Gold Rush when John Marshall discovered gold at Sutter's Mill in Coloma, California. The discovery set off a massive influx of people to the state as they searched for their fortunes in the goldfields.

3. In 1906, on March 15, a massive earthquake measuring 7.8 on the Richter scale struck San Francisco, leading to widespread destruction and fires that burned for days. More than 3,000 people lost their lives and much of the city was left in ruins.

4. On March 15, 1950, the famous actor and comedian Charlie Chaplin was accused of being a communist by the House Un-American Activities Committee. He was subsequently exiled from the United States and moved to Switzerland.

5. March 15, 1964, was the day that the groundbreaking ceremony for what would become the Monterey Bay Aquarium took place. The aquarium, which opened in 1984, is now home to more than 35,000 creatures representing over 550 species of plants and animals from the ecosystems of the California coastline.