you had me at retaining wall... haha. When I was in my late teens I helped my father build a retaining wall that might be the most physically powerful structure in all of North Carolina. If it was a bunker, it would be bomb-proof. We had a lot of fun building that thing and over-reinforced it kind of as a joke. That thing, unless intentionally removed by a lot of excavator work, will be there long after we are all gone.

That is great you are doing that with your kids. You are an exception and an exceptional parent.