What can you do with gold bars?

We already have an answer for a similar question which you can see here:
What are the gold bars for and where are the ones I earned from the team..

If you have more answers to add you can do that below.

The only thing you can do with gold bars is to upgrade or downgrade building facades. If you tap on a building that has already been upgraded 5 times, then tap on the green button with house&hammer icon, you will see the facades and your gold bar count.