BiFeO3 displays an abrupt first order transition from the polar structure R3c to centrosymmetric R (3) over barc at T-C = 830 degrees C. The ferroelectric transition is associated with abrupt changes in polar cation displacements and a large discontinuous volume. A continuous volume expansion occurs across the second order antiferromagnetic transition at T-N = 370 degrees C. Electronic conductivity anomalies are associated with both phase transitions.