Question: when were the first castles built in europe
[{'answer': '9th and 10th centuries', 'provenance': [{'wikipedia_id': '49557', 'title': 'Castle', 'start_paragraph_id': 46, 'start_character': 20, 'end_paragraph_id': 46, 'end_character': 42, 'bleu_score': 1.0, 'section': 'Section::::History.:Antecedents.\n'}]}, {'provenance': [{'wikipedia_id': '49557', 'title': 'Castle', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 796, 'bleu_score': 0.9500142014089771, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7188086143194447084}, 'section': 'Section::::Abstract.'}]}]