Crown Castle International Corp. is a real estate investment trust, which owns, operates and leases shared wireless infrastructure that is geographically dispersed throughout the United States and Puerto Rico. The Company's segments include towers and small cells. As of December 31, 2016, it had approximately 40,000 towers and other structures, such as rooftops (collectively towers) and approximately 26,500 route miles of fiber (collectively small cells, and together with towers, wireless infrastructure). The towers segment provides access, including space or capacity to its towers, which are geographically dispersed throughout the United States. The towers segment also reflects certain network services relating to its towers. As of December 31, 2016, the small cells segment provided access, including space or capacity, to the Company's approximately 17,000 route miles of fiber primarily supporting small cell networks. The small cells segment also offers fiber-based solutions.