We live on the ninth floor, so for the few months since we moved into this apartment, we figured it was OK to leave it unlocked.
We were wrong.
According to this article from the Sydney Morning Herald, there is a thief out there who likes climbing the outside of high rise buildings and entering apartments through the balcony. He has been linked to 16 different robberies.
Here's hoping that our locked door keeps us from being number 17.