Both history buffs and architecture aficionados will thrill to these two fabulous mansions-turned-museums. The first is an imposing Greek Revival home built by colonial-era public official Alexander Macleay in 1835 on a beautiful 22-hectare (54-acre) lot of prime harbor-fronted land. The second is a swoon-worthy 1820s estate still surrounded by the original romantic gardens and wooded grounds. The best part? You don't even have to leave the environs of Sydney Harbour to see these classic gems—they're both set in swanky harborside neighborhoods.