Fernleigh Castle, Victorian mansion in Rose Bay, Sydney, Australia.

Fernleigh Castle is a Victorian house in Rose Bay, Sydney, built in 1892 on the site of an 1874 sandstone cottage whose original walls are incorporated into the new structure. It is built of pink to brown fine dressed sandstone and has a square Norman-style tower, smaller towers with turrets, castellated walls, and wrought iron balconies. The house has thirty rooms and stained-glass windows.

The estate was built in 1892, replacing an earlier cottage from 1874, with portions of the original sandstone walls incorporated into the new construction. This reuse of existing materials connected the new building to the site's prior history.

The mansion displays Victorian design choices through wrought iron balconies and stained glass windows, reflecting the taste of wealthy Australian households in the 1800s. The cedar woodwork and decorative details inside show the craftsmanship that owners of such homes valued and demanded.

Fernleigh Castle is a private residence and is not open to the public, so it cannot be visited inside. The house can be seen from the street in Rose Bay, where the square Norman-style tower, smaller turrets and castellated sandstone walls are visible from outside. The original 1874 cottage walls are incorporated into the later building.

The main bedroom measures 35 by 18 feet and holds a porcelain bath three feet deep, set in a cedar and marble frame of white zinc. The house was built for Charles Warman Roberts, who owned the Roberts Hotel on the site where Gowings later stood in the city.