 They remained in the Royal Chapel while the famous Basilica of the Monastery and the Royal tombs were still under construction.In 1654, after the Basilica and Royal tombs were finally completed during the reign of their great-grandson Philip IV, the remains of Charles and Isabella were moved into the Royal Pantheon of Kings, which lies directly under the Basilica.On one side of the Basilica are bronze effigies of Charles and Isabella, with effigies of their daughter Maria of Austria and Charles's sisters Eleanor of Austria and Maria of Hungary behind them.