Every year Open House in Melbourne allows the public to see buildings that you otherwise might not have the chance. They even have a ballot to get into the most exclusive ones. For alot of they have limits of the group size and long lines. We managed to find a treasure in St Patricks Cathedral. It was warm, with beautiful lighting and lots of seats. Then we went to the Old Treasury building (you can access throughout the year). We found little hidey holes or lent against the walls.
The inside is really amazing with the soft lighting and pillars.