San Fernando Cathedral - San Antonio, Texas - American Guide Series on Waymarking.com

From Texas: A Guide to the Lone Star State, San Antonio section:

SAN FERNANDO CATHEDRAL, on Main Plaza between Trevino and Galan Sts., has the oldest parish church building in the State. The iron cross mounted on the Moorish dome of the earliest part of this Roman Catholic cathedral marks the exact geographical center of the city. In the Villa of San Fernando a parochial church stood here; its cornerstone was laid in 1738. Colonel Francis W. Johnson raised the flag of victory from its towers in 1835 following the Battle of San Antonio; Santa Anna used the church during the Alamo siege, and from its top flew the blood red flag of no quarter. The building as it now appears was completed in 1873 (the rear of the building being original), and the parish church became a cathedral in 1874. In  1936  fragments of bone were disinterred from beneath the floor, believed by some authorities to be remains of Alamo heroes, buried there after their charred bones had been recovered from the site of the funeral pyres.

The Cathedral continues to serve as the Cathedral for the Archdiocese of San Antonio.  The Cathedral has undergone extensive restoration work in the last few years to stabilize and restore the Cathedral for its continued use in the future.  The Cathedral with the walls of the original 1738 church , is the oldest continuously operating cathedral in the United States and the oldest building in Texas.