The archdiocese 's original cathedral church is St. Mary Cathedral Basilica in Galveston with a co-cathedral located in Downtown Houston .
St. Mary Cathedral Basilica in Galveston with a co-cathedral is the Co-Cathedral of the Sacred Heart .
The archdiocese 's original cathedral church is St. Mary Cathedral Basilica in Galveston with a co-cathedral , the Co-Cathedral of the Sacred Heart , located in Downtown Houston .