Bryan Berg builds houses of cards — mansions of cards — and his Cardstacker Gallery has some astounding photos, including a record-breaking 25-foot tower.

When the Christian Science Monitor asked whether he could build a 100-foot tower, he said, “Sure. But it’s going to take a while.”

“I have to look twice before I move,” he says. “I basically go into slow motion.”

(A 100-foot tower could actually be dangerous. The 25-footer took more than 1,500 decks — about 250 pounds — of cards. “With something that big,” Berg says, “if it fell and you were near it, you’d run the risk of being buried.”)

Berg teaches architecture at Iowa State University, but he says his training didn’t help with the cards. Vice versa, actually: “I would even say that the majority of what I know about the structural behavior of real buildings and building materials came from my experiences building with cards.”