Where better to begin than Melbourne Town Hall. It is on the premier corner of Collins Street and Swanston Street. Wikipedia assists.
Construction began in 1867 with the foundation stone lain by Prince Alfred, Duke of Edinburgh. Around 1887 the portico was added, which in 1964 hosted The Beatles appearance to 20,000 hysterical fans.
In 1925 a fire damaged much of the town hall and it was rebuilt with some land and or buildings along Collins Street added.
Of course it is Victorian as it was built during the reign of Queen Victoria but I read that its style is Second Empire and was designed by Joseph Reed, born a Cornishman, and someone called Barnes.
Extras: You can take a free tour of the town hall with terrific guides and even hear the the magnificent 10,000 pipe organ auto played. I can't confirm it but there was also a turntable within the town hall to turn the Lord Mayor's car around in a confined space. The clock was built by Smith and Sons of London.
Slip in a statue of Queen Vic at what was once Her Majesty's Hotel in South Yarra, or in gay old days, Macy's.