Planning fallacy
The Sydney Opera House was expected to be completed in 1963. A scaled-down version opened in 1973, a decade later. The original cost was estimated at $7 million, but its delayed completion led to a cost of $102 million.
History of Sydney
To relieve congestion on the Sydney Harbour Bridge, the Sydney Harbour Tunnel opened in August 1992. The 2.3 kilometer underwater tunnel cost A$554 million to construct. Built to withstand earthquakes and sinking ships, in the early 21st century it carries around 75,000 vehicles a day.