The Flatiron Building

Behold the glorious and groovy Flatiron Building, which was my very close neighbor for a few years. For those of you not in the know, it can be found at 23rd Street, where Broadway and Fifth Avenue converge. To those of us who like to show off our savvy, we can add that it is right by the southwest tip of Madison Square Park. But of course, the building cannot be missed, so that superfluous addition would be relayed by only the most insecure of braggarts, also bent on telling you the year of its completion (1902) and what its original name was (the Fuller Building). Any way you slice it, the Flatiron is a must-see if you visit this city. Plus, if you do, you will know that you are in my old neighborhood, and a lot of my old recycled energy from days past still ricochets like mad off its limestone and terra cotta-glazed facade.
So, anyway, this morning when I passed by it on my way home from the gym (because yes, I still go to my “old” gym despite having moved out of the neighborhood 3-1/2 years ago), I stopped in my tracks and gasped. Something was somewhat off about the building. I was so taken aback that I accosted two tourists (pictured in the lower right a/k/a southeast corner of the photo) (but appearing as a single person in the form of a mutant with a ponytail anchored to its right cheek) and shared my discovery with them in a blend of post-workout endorphin-inspired insanity and my regular run-of-the-mill blathering.
Can you spot what it is that the tourists will take home as their finest and fondest memory of their vacation? (Other than unwittingly meeting the hippest girl in town, of course.) (Clicking on the photo will yield a rather large image, but it may help you in your quest to impress me with your response.)