Boston Properties knows more than beans about real estate. The self-administered real estate investment trust (REIT) buys, develops, and manages mostly Class-A office buildings in large US cities, with its core markets being in Boston, New York, San Francisco, and Washington, DC. As one of the nation's largest office owners and developers, Boston Properties owns around 160 office and office/technical properties with 46.5 million rentable square feet. Its largest tenants include the US government, Bank of America, Biogen, and Citibank. The REIT also owns a handful of retail, hotel, residential properties, as well as land sites for development. The firm's chairman is media czar Mort Zuckerman (U.S. News & World Report and Daily News).