Where is this tower located? Credit: Gary MedlicottConstructed in 1852, this unusual square bluestone lighthouse is one of Melbourne’s oldest surviving public buildings and the second-oldest lighthouse in the state. Until the mid-1920s, a copper timeball on its roof was dropped daily, at precisely one o’clock. Check next week’s quiz for the answer. 367 Collins Street, also known as the Optus Centre, is in Melbourne CBD.