Time Out says
Hyde Park was once a source of food and water for the Gadigal people, and was part of an expansive swampland that spread into Sydney's first tank stream. It is now Australia's oldest public park, gazetted in 1810 and formerly home to Sydney's first racecourse. It was virtually destroyed when dug up to make Sydney's underground railway but was restored and beautified to its current state in 1927 and ever since has offered green grass, blue sky and tinkling fountains to harried CBD workers.
Also home to the Anzac Memorial.