As much as possible, put different departments on different floors or buildings and, ideally, time zones. Encourage the debating of unproductive topics.
e.g., what’s the best way of estimating, tabs vs. spaces, or is method X agile or not Make each team as large and specialized as possible. Don’t allow anyone to do anything they aren’t perfectly trained for. Generalists are the enemy. Show people how little you trust them; by requiring all security and permission requests to be approved by outsourced IT people.