The Flatiron Building opened in 1902 and is one of the most significant architectural wonders in New York City.
In this vintage photograph from 1916, we are looking South down 5th Avenue towards a lonesome Flatiron Building with Madison Square Park on our left and horse drawn carriages as far as the eye can see. For comparison, here is a Google Streetview of how it looks nearly 100 years later.
This photo is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1923. See this page for further explanation.