The Alamo in San Antonio, Texas is famous for the role it played in the Texas revolution. What was the Alamo used for before the revolution?

The Alamo in San Antonio was built as a mission to education Native Americans about Christianity by Spanish missionaries.

After a period of disuse, it became an Army barracks for Spanish sodiers posted to the area.

Eventually it became a true fort and Texan soldiers fought to defend it against the Mexican Army before being overrun.