Rotating black holes in unified theories

Some remarkable properties of the supersymmetric five-dimensional rotating solutions of Beckenridge, Myers, Feet and Vafa are described. The solutions may be under-rotating, in which case they are extreme black holes or over- rotating, in which case they are naked time machines. The geodesics and glo bal structure of the spacetime are analysed, including the possibility of t ime travel by freely falling observers. I argue, following recent work with C. Herdeiro, that the over-rotating solutions cannot be reached from the u nder-rotating black hole solutions by a physical process using a finite amo unt of energy. This would fit in with the Chronology Protection conjecture.