Now dwarfed by 20th-century apartments, Colonial Secretary Alexander Macleay's elegant Greek Revival mansion was one of the finest houses in the colony when it was completed in 1839. The architectural highlight is an exquisite oval entrance saloon with a curved and cantilevered staircase.
The grounds – a sort of botanical garden for Macleay, who collected plants from around the world – extended from the harbour all the way up the hill to Kings Cross. Remnants remain, including a little hidden grotto reached by taking a path leading between 16 and 18 Onslow Ave.