From the Guardian:

In 1956, the New South Wales premier Joseph Cahill announced a competition – open to anyone – to design a national opera house at Bennelong Point in Sydney. There were more than 200 entries and the eventual winner, Jørn Utzon’s concrete shells, took 17 years to realise. But what of the designs that didn’t make the cut? UK-based creative studio NeoMan were commissioned by Budget Direct to research and render seven of those entries, working with Venezuelan architecture specialists Projection Comunicación Arquitectónica to produce the final images, republished with permission below.

All seven at:

Sydney Opera  House Alternatives