Boston Properties is one of the largest landlords and developers in New York City. Its holdings, mostly Class-A office space, include the General Motors Building at 767 Fifth Avenue; 601 Lexington Avenue; the Times Square Tower at 7 Times Square; 510 Madison Avenue; 599 Lexington Avenue; and 399 Park Avenue. Marquee addresses along Park Avenue account for more than 50% of its New York holdings. The firm also developed 250 West 55th Street, a 1 million-square-foot office tower that was one of the few on-spec buildings constructed in Manhattan in the last two decades; it opened in 2014. Boston Properties was founded in Boston by Mort Zuckerman, its current chairman and chief executive, and Edward Linde, who died in 2010. It has numerous other, mostly office, holdings nationwide. Since 1997, it has operated as a real estate investment trust (REIT), headquartered in Boston, Massachusetts, and is listed on the New York Stock Exchange under the ticker symbol BXP. WP