Beginning in 1689, in response to fears of French incursion into its colonial territories, Spain began constructing missions in the eastern part of present-day Texas. Though many of these missions have not survived to the present day, there are several that have been preserved as historical sites. You can visit two of the most famous missions, the Espiritu Santo de Zuniga mission and the Mission Rosario, in Goliad State Park.
Many of Texas' historical sites are commemorative in nature, denoted to mark important historical figures and events. You can see President Lyndon Johnson's grave in the National Historical Park, or Monument Hill, which honors the fallen soldiers of the Battle of Salado. There is the San Jacinto Monument, which sits on the battleground where Texas ultimately won its independence from Mexico, or you can visit the birthplace of Gen. Ignacio Zaragoza, who is revered as a Mexican hero.
Having been a vital part of the history of the military conflicts between the United States and Mexico, as well as the American Civil War, Texas has many important sites dedicated to military history. There is Fort Richardson in Jacksboro, which played an important role in conflicts with the Comanche Indians. You can visit the Battleship "Texas," a dreadnought that served in both World Wars that is now anchored in the Houston Shipping Channel near San Jacinto State Park. Of course, there is also The Alamo in San Antonio, one of Texas' most famous historical sites.
Despite its reputation of having an arid and vast desert climate, Texas is home to a wide variety of landforms and was amenable to ancient human settlements. There are many examples of cave drawings and pictographs for you to explore, including the Big Bend Ranch in Presidio, the rock painting at Devils River, the mask collection and rock labyrinth at Hueco Tanks and Seminole Canyon in Comstock.