I’d recommend assembling on its side, a lot of folks who gave lower star reviews said pieces weren’t cut properly etc. but in my experience you might have to rescrew a few of the panels but it all eventually fits nicely together. I highly recommend assembly on the groundhorizontal, that was the easiest for me. Seems sturdy where it needs to be, the top part of the shelf (free floating plank) others complained about is still holding strong for me. I would recommend a power drill or two other people to switch off with the screwdriver, as your hand will be numb after assembly, so many screws!