DUBAI - Saudi billionaire Prince Alwaleed bin Talal says he is looking at the world’s largest cities, including Shanghai, Moscow, London and New York, as possible locations to build a mile-high skyscraper that would be the world’s tallest building by far. The prince is inviting Dubai’s biggest real estate developer Emaar Properties, chaired by Mohammed Alabbar, to team up with his investment firm Kingdom Holding on the project.