Aborigines on the southern side of Port Jackson (Sydney Harbour) called the north side warung which meant the other side, while those on the northern side used the same name to describe the southern side.
The first name used by European settlers was Hunterhill, named after a property owned by Thomas Muir (1765–1799), a Scottish political reformer. He purchased land in 1794 near the location of north pylon of the Sydney Harbour Bridge is now located, and built a house which he named after his childhood home. This area north to Gore Hill became known as St Leonards.
The North Sydney municipality was incorporated in 1890 and after naming disputes, North Sydney was settled upon. The post office which opened in 1854 as St Leonards was changed to North Sydney in 1890. The first public school which opened in 1874 as St Leonards was renamed North Sydney in 1910.
North Sydney underwent a dramatic transformation into a commercial hub in 1971-72. In this period no less than 27 skyscrapers were built (Wikipedia).