Tomorrow (Tuesday) will be fifty years to the day since the Sydney Opera House topped out when the final section of the tallest sail of the Opera House roof was fitted and bolted into place. It was anticipated that the Opera House would be ready within a year of the photo being taken, but was not completed until 1973.
Source: Anonoyous. 1966. "Top Note on the Opera House." The Daily Telegraph, April 6: 5.