The building we know today as the Alamo began in 1718 as mission San Antonio de Valero, located on the San Antonio River in what was then known as the Spanish province of Tejas (Texas).  After secularization in 1793, the mission compound was used to garrison soldiers that the Spanish government sent from a small town called Alamo de Parras in southern Coahuila. The mission buildings and plaza were gradually transformed into a fort that became known as the "Alamo". The first hospital in Texas, although military, was established at the Alamo in 1805. The Alamo remained in Spanish hands until 1821 when Mexico finally gained its independence from Spain.

In 1832 General Antonio López de Santa Anna began his rise to power when he overthrew the existing Mexican government.  For the next several years the citizens of Tejas began to voice their concerns over his strict dictatorial reign.  Many Anglo colonists and Tejanos wanted  separate Mexican statehood for Tejas, and some even favored independence.

As tensions rose between the Mexican government and the colonists, General Santa Anna sent troops to end the insurrection. The Mexican soldiers strengthened San Antonio de Béxar, including the old Spanish mission now called the Alamo. This Mexican force was eventually defeated and Texas patriots took control of the Alamo. 

Men began to arrive in San Antonio and volunteer to help in it's defense.  Lt. Col. William Barret Travis assumed partial command of the garrison along with Jim Bowie, both of whom had been residing in Texas.  To this group was added a former American Congressman and legendary frontiersman, David Crockett along with volunteers from Tennessee.  These men knew that Santa Anna and his army was marching to take back the installation and punish the colonists.

General Santa Anna and his advance forces reached San Antonio on February 23, 1836.  The siege of the Alamo was about to begin.  The defenders were a mix of Anglos and Tejanos from all walks of life and, they came from Texas, the United States and Europe.  For the next two weeks Mexican canons bombarded the Alamo, and on March 6 some 2,500 Mexican troops stormed the stronghold.  All 189 Alamo defenders were killed.

In 1850, the United States Army Corps of Engineers, added the familiar arched top to hide a new roof.  The building was used as a store house for many years after.

The memory of that great battle provided inspiration to General Sam Houston's troops on April 21, 1836 at San Jacinto. The cry of "Remember the Alamo" was heard across the battlefield as Houston defeated Santa Anna and gained independence for Texas.  2011 marks the 175th anniversary of the fall of the Alamo.