Complex sentence: The road was improved by Major Druitt in 1820 to gave faster access to the signal station at South Head, and also gave access to the salubrious villas built by the colony's emerging plutocracy.
Split into simpler sentences: The road was improved by Major Druitt in 1820 to gave faster access to the signal station at South Head. It was also to give access to the salubrious villas built by the colony's emerging plutocracy.