Downtown bar Moses Roses Hideout sits in the footprint of the $150 million Alamo Visitor Center and Museum project. Credit: Instagram / officialalamo

A centuries-old mystery about the origins of the limestone used to build the Alamo was put to rest Thursday when the site’s overseers revealed on Good Morning America that the material came from a quarry at the site of the present-day San Antonio Zoo.

The discovery was made while constructing the zoo’s much-anticipated gorilla habitat and new event center. The Alamo conservator Pam Rosser saw the limestone being dug up from the Congo Falls construction site and thought it looked familiar.

“Historians always guess that the original stone used to build the Alamo came from this area,” GMA reporter Matt Rivers said. “They just weren’t sure exactly where.”

To verify suspicions, New York-based Highbridge Materials Consulting Inc. was contracted to conduct comprehensive geological and material analysis to compare the stone found at the zoo to the material at the Alamo. The tests came back a match.

“This discovery deepens our understanding of the Alamo’s origins and reinforces the strong historic ties between our city’s landmarks,” Alamo Trust Executive Director Kate Rogers said in a statement. “For the first time, we can say with confidence that this quarry, now part of the San Antonio Zoo, supplied the materials that built one of the most recognizable historical sites in the United States.”

The discovery comes at an important time since the walls of the Alamo, now undergoing a $550 million redevelopment, are slowly deteriorating.

“The stone needs replacing,” reporter Rivers said during the GMA segment. “But, you can’t just patch it up with new material. You need the same limestone that was used back in the 1700s.”

To preserve the Alamo, the limestone extracted during the construction of the Zoo’s Congo Falls exhibit will be transported to the historical site to help with ongoing restoration efforts.

“The San Antonio Zoo, which has been part of our community for over a century, is honored to play a role in uncovering this important piece of Texas and world history,” San Antonio Zoo CEO Tim Morrow said in a statement.

Subscribe to SA Current newsletters.

Follow us: Apple News | Google News | NewsBreak | Reddit | Instagram | Facebook | Twitter| Or sign up for our RSS Feed

Related Stories

This article appears in Mar 5-18, 2025.

Michael Karlis is a multimedia journalist at the San Antonio Current, whose coverage in print and on social media focuses on local and state politics. He is a graduate of American University in Washington,...