1100 Superior (formerly known as the Diamond Shamrock Building, the Diamond Building, and Oswald Centre) is a skyscraper in downtown Cleveland, Ohio's emerging Nine-Twelve District, which is also home to One Cleveland Center, Ohio Savings Plaza, The 925 Building, PNC Center, and the former Eaton Center. It was built in 1972 for the important San Antonio, Texas firm of Diamond Shamrock which specialized in oil refining, it has 23 floors and rises to a height of .
1100 Superior (formerly known as the Diamond Shamrock Building, the Diamond Building, and Oswald Centre) is a towering structure in Cleveland's developing Nine-Twelve District, which also features One Cleveland Center, Ohio Savings Plaza, The 925 Building, PNC Center, and the former Eaton Center. Constructed in 1972 for the prominent San Antonio-based oil refining firm Diamond Shamrock, it has 23 floors and reaches a height of .