Question: when was the western wall built in jerusalem
[{'answer': '19 BCE', 'provenance': [{'wikipedia_id': '75225', 'title': 'Western Wall', 'start_paragraph_id': 2, 'start_character': 1116, 'end_paragraph_id': 2, 'end_character': 1122, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]