In what year was the Astrodome opened?

The Astrodome is a domed sports stadium, the first of its kind. It is located in Houston, Texas at 29.6849° N 95.408° W, and is now part of the Reliant Park complex. It opened in 1965 as Harris County Domed Stadium and was nicknamed the "Eighth Wonder of the World". (A team owner is quoted as saying that the "rent for the Astrodome was the ninth".) Reliant Energy purchased naming rights to the building in 2000.