The Alamo is a must see. As is the 150 year old bar in the historic Menger Hotel right next door to the Alamo.

Teddy Roosevelt and his Rough Riders volunteers used it for drinking while in San Antonio before heading to charge up San Juan Hill.
And quite a few other famous visitors, too.
Including:
Ulysses Grant, Robert E Lee, Sam Houston, Benjamin Harrison, Woodrow Wilson, William H. Taft, William McKinley, Harry Truman, Richard Nixon, Ronald Reagan, Lyndon Johnson, military figures, and William Hood Simpson; and other public figures, including Oscar Wilde.

"Allways speak the truth and you will never have to remember what you said before..." Sam Houston
Texans, "We say Grace, We Say Mam, If You Don't Like it, We Don't Give a Damn!"

~Molɔ̀ːn Labé Skýla~