>And I wonder why the Americans build a whole city in a soup bowl, ...

Acutally it was the French who founded New Orleans.

New Orleans was founded in 1718 by the French as La Nouvelle-Orléans, under the direction of Jean-Baptiste Le Moyne de Bienville. The site was selected because it was a rare bit of natural high ground along the flood-prone banks of the lower Mississippi, and was adjacent to a Native American trading route and portage between the Mississippi and Lake Pontchartrain via Bayou St. John (known to the natives as Bayou Choupique). A community of French fur trappers and traders had existed along the bayou (in what is now the middle of New Orleans) for at least a decade before the official founding of the city. Nouvelle-Orléans became the capital of French Louisiana in 1722, replacing Biloxi in that role.

http://en.wikipedia.org/wiki/History_of_New_Orleans

We just built the wood houses.