Build a Spiral Wine Cellar or Secret Club House Under Your Kitchen
The possibilities with this are endless. Legos timeout when you’ve stepped on one too many sharp little blocks laying about, awful guests at holiday dinners (“What’s that darling? Can’t hear you. Can you get a couple of bottles of Chardonnay while you’re down there? I’m going to check on the turkey.”), Halloween decorations you have no storage space for anymore (creepy zombies with glowing eyes, sure to freak out your visitors).
Besides the price, I think a silo under my concrete slab wouldn’t fly with He Who Is In Charge of Me.