Namely the Empire State Building, the Pentagon, and the Washington National Cathedral have in common that they were all built with natural Indiana limestone.Indiana limestone continues to be used and desired in today architecture.Indiana limestone provides innovative design solutions for architects and designers, and has a long kinship as the masons friend, since it's a durable, natural stone thats readily available and easy to work in the field.When specifying Indiana limestone, it is necessary to identify the color and grade required, as well as the surface finish to be applied to the stone.