Detailed Instructions: This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
Q: Passage: Some other popular sights are the Waterloo Column, the Laves House, the Wangenheim Palace, the Lower Saxony State Archives, the Hanover Playhouse, the Kropcke Clock, the Anzeiger Tower Block, the Administration Building of the NORD/LB, the Cupola Hall of the Congress Centre, the Lower Saxony Stock, the Ministry of Finance, the Garten Church, the Luther Church, the Gehry Tower (designed by the American architect Frank O. Gehry), the specially designed Bus Stops, the Opera House, the Central Station, the Maschsee lake and the city forest Eilenriede, which is one of the largest of its kind in Europe. With around 40 parks, forests and gardens, a couple of lakes, two rivers and one canal, Hanover offers a large variety of leisure activities.
A:
Who was the Austrian architect who built the Gehry Tower