New York 1901: Flatiron (Spielbox #5, 2015 version) is a mini-expansion for New York 1901 that consists of:
1 Legendary Skyscraper, namely the Flatiron Building
3 Bonus Challenge cards: Big Developer, Real Estate Mogul, Silver Titan
The cards and the tile come in a plastic bag.
English rules in English spielbox
German rules in German spielbox