San Antonio de Valero Mission (originally referred to as San Antonio de Padua) was authorized by the viceroy of Mexico in 1716. Fray Antonio de Olivares , who brought with him Indian converts and the records from San Francisco Solano Mission near San Juan Bautista on the Rio Grande, established the mission at the site of present-day San Antonio on May 1, 1718, and named it San Antonio de Valero in honor of Saint Anthony de Padua and the Duke of Valero, the Spanish viceroy. After a hurricane destroyed most of the existing buildings, the mission moved to its present site in 1724; the cornerstone of the chapel was laid on May 8, 1744. The original chapel suffered a structural collapse in the mid-1750s. Reconstruction efforts began in earnest in 1758 but were never completed. Founded for the purpose of Christianizing and educating the Indians, the mission later became a fortress and was the scene of many conflicts prior to the siege of 1836. Its activity as a mission began to wane after 1765, and it was secularized in 1793, and the archives were removed to nearby San Fernando Church.
In 1803 the Second Flying Company of San Carlos de Parras, a company of Spanish soldiers from Álamo de Parras, Coahuila, Mexico, occupied the abandoned mission and used its buildings as barracks for a number of years. From this association probably originated the name Alamo.
According to some historians, the name derived from a grove of cottonwood trees growing on the banks of the acequia. Álamo was the Spanish word for "cottonwood." Spanish and Mexican forces occupied the Alamo almost continuously from 1803 to December 1835, when Gen. Martín Perfecto de Cos surrendered the fortress to Texan forces.
On February 23, 1836, Mexican forces under the command of Gen. Antonio López de Santa Anna besieged Col. William B. Travis and his Texas garrison in the Alamo. The siege of the Alamo lasted thirteen days and ended on March 6 with a complete loss of all the combatant Texans (see ALAMO, BATTLE OF THE).
After the fall of the Alamo, the building was practically in ruins, but no attempt was made at that time to restore it. The Republic of Texas, on January 18, 1841, passed an act returning the chapel of the Alamo to the Catholic Church. After Texas was annexed to the United States, the Alamo was declared property of the United States government. During the Mexican War the United States Army occupied the building and grounds and until the Civil War used them for quartermaster purposes. For some time the city of San Antonio, the Catholic Church, and the United States government all claimed the Alamo. The United States government finally agreed to lease the property from the Catholic Church and made some improvements. These included a new roof for the chapel and convent (also known as the Long Barrack), repairs to the chapel’s stone walls, and the addition of the chapel’s iconic arched gable. An 1855 court decision later reaffirmed the Catholic Church’s rightful ownership of the structure. During the Civil War the Confederates used the building, but after the close of the war the United States government again took over and used it until 1877, when quartermaster operations moved to the permanent army post that was eventually designated Fort Sam Houston. In the ensuing decades, much of what remained of the original Alamo site, including the remnants of the outer walls and central courtyard, was consumed by the development of Alamo Plaza and the construction of new city streets and businesses. By the late 1880s, the only original elements still standing were the Long Barrack and the iconic chapel. In 1877 the Catholic Church sold the Long Barrack to French merchant Henri Grenet, who remodeled it to house a general store. Grenet also leased the chapel for use as a warehouse. After his death in 1882 the remodeled Long Barrack was acquired by the mercantile firm Hugo & Schmeltzer; control of the chapel reverted back to the Catholic Church.
Under an act of April 23, 1883, the state of Texas purchased the Alamo chapel from the Catholic Church and placed it in the custody of the city of San Antonio on condition that the city should care for the building and pay a custodian for that purpose. This system continued until January 25, 1905, when the Texas legislature passed a resolution ordering the governor to purchase the Long Barrack. It was further ordered that the governor should deliver the property thus acquired, with the property then owned by the state (the chapel of the Alamo), to the Daughters of the Republic of Texas (DRT), who were entrusted with its care, maintenance, and preservation.
A controversy over custody of the Alamo developed almost immediately between the Daughters of the Republic of Texas and the De Zavala chapter of that organization at San Antonio. The disagreement revolved around the disposition of the Long Barrack—while one faction sought to demolish much of the structure to make way for a public park, another proposed that it should be restored to its original appearance. The resulting legal battle drew the involvement of Governor O. B. Colquitt, who agreed that the Long Barrack should be fully restored and temporarily suspended the DRT’s custody of the property. In 1912 the Fourth Court of Civil Appeals resolved the matter and reinstated the DRT’s custodial rights. Ultimately, the DRT decided to demolish the second floor of the Long Barrack and reconstruct the walls of the first floor between 1913 and 1916. Public exhibits to draw visitors and tourists to the site began about 1915. In 1921 construction crews added a new concrete, barrel-vaulted roof to the chapel to replace the wooden roof constructed by the U.S. Army, and installed electric lighting.
Several appropriations for funds to improve the Alamo have been made, the largest being in connection with the celebration of the Texas Centennial. Between 1925 and 1937 a combination of federal, state, municipal, and private funds were used to purchase and consolidate surrounding properties for the expansion of Alamo Plaza and creation of a museum complex. Beautification efforts included new landscaping on Alamo Plaza and the construction of an enclosed garden to the east of the chapel. Within the enclosed space the construction of several new structures included a restored section of acequia, the Alamo Museum (later converted into a gift shop), the Arcade (a Works Progress Administration project that since 1997 has housed the “Wall of History”), and Alamo Hall (a remodeled fire station deeded by the city of San Antonio in 1938 that as of 2018 served as an event venue). The chapel also received a new flagstone floor and a new outer roof of copper and lead over the north rooms. The 1930s expansion effort culminated with the installation of the Alamo Cenotaph, sculpted by renowned artist Pompeo Coppini and formally dedicated in November 1940. Post-1940 additions include the construction of the DRT Library in 1950 and the installment of a museum in the Long Barrack in preparation for HemisFair '68. An outdoor amphitheater was added to the Alamo gardens in 1997.
Today the 4.2-acre Alamo complex is considered one of the most popular tourist destinations in the state of Texas and has received designations as a National Historic Landmark (1960), a Texas Historic Landmark (1962), and a Texas State Antiquities Landmark (1983). In 1966 it was listed on the National Register of Historic Places (NRHP), and in 1977 it was included in the NRHP’s newly-designated Alamo Plaza Historic District. On July 5, 2015, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) declared the Alamo and the missions of San Antonio Missions National Historical Park a World Heritage Site—the first such designation in Texas.
The Alamo complex remained in the custody of the Daughters of the Republic of Texas until 2011, when the Texas legislature transferred this authority to the General Land Office (GLO), which contracted the DRT to continue overseeing day-to-day operations. In 2012 the private, nonprofit Alamo Endowment was established to assist the GLO with fundraising, preservation, maintenance, and long-term planning for several much-needed physical improvement projects. From 2011 to 2017 these included renovations to the Alamo chapel, the Long Barrack Museum, the Alamo Museum and gift shop, Alamo Hall, and the DRT Library (later renamed the Alamo Research Center). In 2015 the GLO terminated its contract with the DRT and transferred responsibility for daily operations to Alamo Complex Management (later renamed the Alamo Trust), a subsidiary of the Alamo Endowment. Also in 2015 the state legislature approved the first of two appropriations totaling more than $106 million to fund ongoing improvements. In 2017 the GLO, Alamo Endowment, and city of San Antonio unveiled a joint master plan that would significantly redevelop much of the existing Alamo complex and Alamo Plaza Historic District. In addition to continued preservation of the Alamo chapel and Long Barrack, the ambitious plan proposed relocating nearby entertainment venues, restricting vehicle traffic, construction of a 135,000-square-foot visitor center and museum, and archaeological excavations to reveal long-buried remains of the original mission structures. Some elements of the plan, including a controversial proposal to relocate the Alamo Cenotaph, were still under consideration as of 2018.