Task: Question Generation
Input (English): John grew up to be around 5 ft 5 in (1.68 m) tall, relatively short, with a "powerful, barrel-chested body" and dark red hair; he looked to contemporaries like an inhabitant of Poitou. John enjoyed reading and, unusually for the period, built up a travelling library of books. He enjoyed gambling, in particular at backgammon, and was an enthusiastic hunter, even by medieval standards. He liked music, although not songs. John would become a "connoisseur of jewels", building up a large collection, and became famous for his opulent clothes and also, according to French chroniclers, for his fondness for bad wine. As John grew up, he became known for sometimes being "genial, witty, generous and hospitable"; at other moments, he could be jealous, over-sensitive and prone to fits of rage, "biting and gnawing his fingers" in anger.[nb 3]
Output (English): What did John build up?