A ceremonial stone set at the corner of a building, joining two exterior walls, and often inscribed with the starting and completion dates of construction, the name of the architect and owner, and other details.The cornerstone on the Flatiron Building is set on the Fifth Avenue facade.
By extension, that which is prominent, fundamental, noteworthy, or central.Exceptional service is the cornerstone of the hospitality industry.That is the cornerstone of any meaningful debate about budgets and projects, regulations and policies.
