Complex sentence: Marie, however, did not comply, instead retreating to Bran Castle and to Balchik, where she had built a palace and a small chapel called "Stella Maris" and tended to her garden.
Split into simpler sentences: Marie, however, did not comply, instead retreating to either of two residences. The other was Balchik, where she had built a palace and a small chapel called "Stella Maris" and tended to her garden.