Hanson plc (formerly Hanson Trust plc) is a British base international building materials company, headquartered in London. Traded on the London Stock Exchange and a constituent of the FTSE 100 Index for many years, the company was acquired by a division of German rival Heidelberg Cement in August 2007. Before a series of demergers in the 1990s Hanson was a conglomerate with a diverse range of subsidiaries, and one of the very largest British companies.