Question: what was the tower of london originally used for
[{'answer': 'a royal residence', 'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 1, 'start_character': 794, 'end_paragraph_id': 1, 'end_character': 811, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'as a royal residence', 'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 1, 'start_character': 791, 'end_paragraph_id': 1, 'end_character': 811, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1156, 'bleu_score': 0.9904073966945661, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7354648929830740949}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 23, 'start_character': 0, 'end_paragraph_id': 23, 'end_character': 1172, 'bleu_score': 0.9897694846447971, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7354648929830740949}, 'section': 'Section::::Foundation and early history.\n'}]}, {'provenance': [{'wikipedia_id': '6597772', 'title': 'Tower of London (disambiguation)', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['The Tower of London is a former Royal residence in London.', 'The Tower of London is a former Royal residence in London.\rhighlight sentence(s) containing evidence, not only the answer', 'The Tower of London is a former Royal residence in London.']}}]}, {'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ["The Tower of London, officially Her Majesty's Royal Palace", "The Tower of London, officially Her Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle located on the north bank of the River Thames in central London."]}}]}]