The Conciergerie was used as a prison for condemned prisoners including Ravaillac, Marie-Antoinette and Danton. It has retained superb remains from the 14C, notably the Guards' Room, Hall of the Soldiers and kitchens. The façade boasts four towers: the crenellated Bonbec Tower, housing the torture chamber; the Silver Tower, home to the royal treasure; the Caesar Tower; and the square Clock Tower (the first public clock in Paris was installed here in 1370).