The Cornstalk has a different architecture than the rest of the French Quarter because it was built sometime after the Lousiana Purchase in 1803 and before the organization that says "Hey, you can't build a building like that here!" came into being (I have forgotten their name, it is French for either "Useless Government Interference into Your Property Rights" or "Concerned Residents Who Want to Maintain the Charm and Allure of the French Quarter" take your pick.)