Towers and bridges

We had a staff development day with another organisation today, and part of the "getting to know you" (we knew each other by email but had never met in most cases) we had to build two towers in teams. Both had to be over 30cm. My team went for height in one case and stability in the other. The second part of the task (which we didn't know til after the tower building) was to build a bridge between the two which was strong enough to hold a phone for 30 seconds. You may not believe it looking at it but ours did actually manage to hold a phone for far longer than 30 seconds! Despite competitive colleagues coming and jumping beside it and attempting to blow it over. I'm not sure what the lesson was but I'm sure we learned one.