Fund cross team retreats
My employers, Thoughtworks, organise company-wide events called away days, which I must admit are harder to organise as the company gets bigger. The logistics get too complicated and people can get lost in a sea of unfamiliar faces. Depending on the size of your company, you may need to split up these retreats by team or department. Regardless of how you execute them, make sure you do them. The value far outweighs the cost as some research already shows.
You’ll find Chase Warrington’s advice very helpful, if you plan to organise any of these events.