Passage: For the 1972 Summer Olympics the city of Munich built the Olympiastadion. The stadium, renowned for its architecture, was inaugurated in the last Bundesliga match of the 1971–72 season. The match drew a capacity crowd of 79,000, a total which was reached again on numerous occasions. The stadium was, in its early days, considered to be one of the foremost stadiums in the world and played host to numerous major finals, such as that of 1974 FIFA World Cup. In the following years the stadium underwent several modifications, such as an increase in seating space from approximately 50% to ca. 66%. Eventually, the stadium had a capacity of 63,000 for national matches and 59,000 for international occasions such as European Cup competitions. Many people, however, began to feel that the stadium was too cold in winter, with half the audience exposed to the weather due to lack of cover. A further complaint was the distance between the spectators and the pitch, betraying the stadium's track and field heritage. Renovation proved impossible, as the architect Günther Behnisch vetoed major modifications of the stadium.

Question: who is the architect who proved renovation impossible?
Günther Behnisch