MEDAN , Indonesia's fourth largest city, occupies a strategic point on Sumatra's northeast coast and is a major entry point for boats and flights from Malaysia. It has acquired a reputation for being filthy and chaotic, but also holds some glorious examples of nineteenth-century colonial architecture, built by the Dutch gentry, who grew rich on the back of the vast plantations that stretch up the slopes of the Bukit Barisan to the west of the city. The boom was started by the entrepreneurial Jacob Nienhuys, who saw the potential for tobacco plantations, prompting even the local royalty to migrate to the city to be nearer the action.