Angiopteris evecta (also known as King fern or Giant fern) was thought to be extinct in the wild in NSW until a single plant was discovered in 1978. It can also be found growing in rainforests in Queensland. Angiopteris is considered to be a primitive species which goes back to the ancient Gondwana flora. This specimen can be found in the Bicentennial Conservatory in Adelaide Botanic Gardens.
And this is the Conservatory from the outside!