Crown Castle International Corp. is a real estate investment trust. The Company owns, operates, and leases shared wireless infrastructure, including towers and other structures, such as rooftops (towers) and small cell networks supported by fiber. The Company operates through U.S. operations segment. The Company also offers certain network services relating to its wireless infrastructure, consisting of site development services relating to existing or new tenant equipment installations on its wireless infrastructure, including site acquisition, architectural and engineering, or zoning and permitting (collectively, site development services), and tenant equipment installation or subsequent augmentations (collectively installation services).The Company's business is providing access, including space or capacity to its wireless infrastructure in the United States. It also offers fiber solutions, including dark fiber and lit fiber.