If your organisation has a problem with silos – that is to say, you are dealing with departments caring mainly about their internal processes and KPIs, blaming poor results on others, not aligning around what success looks like -, the best way to break down the silos is to start a project that needs the input and commitment of people that come from the different silos.
Make them know each other, come up with ideas and execute in the same space, define success and celebrate together.
It will teach them empathy for other functions and it will allow them to take that empathy back to their respective teams.