Despite it's name, the French Quarter, New Orlean's oldest neighborhood, has only a handful of buildings that remain in the French colonial style of our founding fathers.  The major events influenced the transformation of theQuarter's build environment – Louisiana Purchase, fires of 1788 & 1794. 

The spaniards enforced strict building codes (ex: brick!) to avoid fire, the architecture was indirectly influenced by the spanish, by way of the carribean. The creole architecture (mix of spanish, french, and carribean) is what the quarter is made of today (since mid 1800's?)  Compare to Havana or Cartagena. This is the time wrough iron became popular