The imposing limestone Quadrangle shelters one of the most tranquil places in San Antonio. Built in 1876, it is the oldest building in Fort Sam Houston and has for over a century been both an integral Army center as well as a free and open wildlife garden.

The Quadrangle was the original fort at Sam Houston, and was designed without windows to better withstand attacks. It was originally a quartermaster’s depot, storing housing supplies, and later it became an arsenal for the US Army.

Then, for six weeks in 1886, the Apache leader Geronimo was held at the Quadrangle following his surrender. According to popular stories, the deer were brought to the Quadrangle to make Geronimo feel more at home. Another story has the deer being introduced for Geronimo and the thirty other captured Apaches to hunt, as they wouldn't eat the Army food. However, the truth of why the deer and other delicate animals were brought onto the military compound remains a mystery. Whatever the real story, they have been wandering the grassy square since before Geronimo's imprisonment.

The deer, rabbits, peacocks, and other birds walk freely in the grass and under the trees here, tame enough that many of them will crowd around visitors at the sight of food. At the center of the grounds is a brick clock tower with a plaque at its top commemorating the construction of the Quadrangle, although it’s too high for anyone to read.

Fort Sam Houston continues to serve as an active military base: The building is currently the headquarters for the United States Army North.