The Flatiron Building was finished in 1902 and opened to tenants on October 1, 1902. It was first called the Fuller Building, after George A. Fuller. The architect was Daniel Burnham's firm.
The triangle shape comes from the site. Broadway cuts across the city grid on a diagonal, so the block is a wedge. It was first 20 stories plus an attic, and grew to 22 stories in 1905.
Early on it was nicknamed Burnham's Folly, because people doubted a building so thin could stand. It is now a National Historic Landmark.

