63 Nassau Street Building was built with an Italianate style cast-iron front facade. It is almost certain that it was designed by James Bogardus, the pioneer of cast iron architecture in America, making it an extremely rare extant example of the work of Bogardus. It it one of the oldest surviving cast-iron-fronted buildings in the city, and one of the very few located in Lower Manhattan, the oldest part of the city and its original financial center.