Mariana was born on 21 December 1634 in Wiener Neustadt, Austria, as the second child of Ferdinand III, Holy Roman Emperor, and Maria Anna of Spain, the sister of Philip IV of Spain. Maria had six children, of whom only Mariana and two sons survived into adulthood: Ferdinand (1633–1654), and Leopold (1640–1705), who became emperor in 1658.[4] Philip's first wife, Elizabeth of France, died aged 41 in 1644.