The Artwork That Spawned 9/11 Conspiracy Theories and Mystery

O n the morning of March 19, 2000, Florian Reither learned what it felt like to scrape the sky. He’d just stepped out of the 91st floor of the North Tower of the World Trade Center through a hollowed-out window. Now, as Sunday’s dawn cracked, Reither — dressed in a brilliant-white leather jacket and matching jeans — stood on a makeshift wooden balcony. It protruded a few feet toward the horizon. Looking down was OK, but gazing up made him nauseous. So he stared straight ahead, locking eyes with the...