Why was San Juan bautista built?

Answer 1

First, the Spanish were afraid that other countries might take over their land, so they build the missions. Last, they wanted to teach the Spanish ways.

Answer 2

San Juan Bautista was built as a Spanish mission in 1797 in present-day California to spread Christianity to the native populations and colonize the region. It was part of the chain of 21 missions established by the Spanish in California.