Item 2. PROPERTIES

On November 1, 2013, we purchased a new headquarters in Boca Raton, Florida where we currently own approximately 160,000 square feet of office space. We have entered into long-term leases for international, regional, and certain site development office locations where we expect our activities to be longer-term. We open and close project offices from time to time in connection with our site development business. We believe our existing facilities are adequate for our current and planned levels of operations and that additional office space suited for our needs is reasonably available in the markets within which we operate.

Our interests in towers and the land beneath them are comprised of a variety of fee interests, leasehold interests created by long-term lease agreements, perpetual easements, easements, licenses, rights-of-way, and other similar interests. As of December 31, 2015, approximately 73% of our tower structures were located on parcels of land that we own, land subject to perpetual easements, or parcels of land that have an interest that extends beyond 20 years. The average remaining life under our ground leases, including renewal options under our control, has been extended to 33 years. In rural areas, support for our towers, equipment shelters, and related equipment requires a tract of land typically up to 10,000 square feet. Less than 2,500 square feet is required for a monopole or self-supporting tower of the kind typically used in metropolitan areas for wireless communications towers. Ground leases are generally for an initial term of five years or more with five or more additional automatic renewal periods of five years, for a total of thirty years or more.