A Blocky Tower

I spotted a small wooden box full of colorful domino tiles lying forgotten near the base of the bookshelf. Instead of jumping around this afternoon, I sat flat on the smooth floor and set to work. I stacked three blue tiles horizontally to form a sturdy base, then laid two red ones across them like tiny crossbeams. One green piece wobbled as I stood it on top, tipping over with a soft click and knocking the red beam askew. No problem at all. I nudged the base back into line and tried an interlocking square pattern instead. It holds surprisingly firm.