Question: when was the tower bridge in london built
[{'answer': 'between 1886 and 1894', 'provenance': [{'wikipedia_id': '60646', 'title': 'Tower Bridge', 'start_paragraph_id': 1, 'start_character': 74, 'end_paragraph_id': 1, 'end_character': 95, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '60646', 'title': 'Tower Bridge', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 613, 'bleu_score': 0.873824282700393, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11345990236603895552}, 'section': 'Section::::Abstract.'}]}]