Sears, Roebuck and Co. announced plans Monday to sell Sears Tower, its corporate headquarters and the world's tallest building, as part of an effort to streamline the company. Sears' restructing plan also will include a stock buyback, "intense cost-cutting" programs and the sale of its commercial real estate subsidiary, the nation's largest retailer said. "We are acutely aware of investors' desires for improved returns and enhanced share value," Edward Brennan, chairman and chief executive officer, said in a statement. "And we have thoroughly evaluated all strategic and financial alternatives available to the company." The Sears Tower, which rises 110 stories - 1,450 feet - from the grid of Chicago's downtown Loop business district, was built in 1974. Brennan's statement did not indicate how much Sears hoped to get for the building.