Final answer:
The popular fort in California is the El Presidio Real de San Francisco, built by the Spanish in 1776 and later taken over by the US Army in 1846, which remained active until 1994. It played a significant role during the settlement and military events of the time, including the Gold Rush.
Step-by-step explanation:
The popular fort in California that served as a major stopping point for travelers is El Presidio Real de San Francisco, commonly known as Fort Presidio. Built by the Spanish in 1776, this fort offered strategic military advantages due to its location on a peninsula between the Pacific Ocean and San Francisco Bay. The fort was later seized by the US Army in 1846 during the Mexican-American War and remained a military base until 1994. El Presidio served not only for defense but also played a role in aiding the influx of settlers during various periods such as the Gold Rush. This was a time when many people, including Californios and migrants from places like Europe, China, and South America, were drawn to California in search of wealth and new opportunities.