Near the St. Louis Cathedral in Jackson Square is a building built about 1815 with Spanish money; I can't remember the name of the builder. In any case, Spanish funds were important in N. O. around this time. Also the Cabildo, where the Spanish council met, built in 1799 (Spanish control from 1762-1800). The French had it back for less than 5 years before they sold out to the U. S. Throughout the period, to about 1825, Spanish investors were important. By 1810, New Orleans was the largest Southern city (only 10,000).

Houses with crawl spaces beneath were common throughout the South; for air circulation and to partly check insects such as termites.

The famous Shotgun houses of New Orleans had 2-3 feet space beneath them. Lots were narrow, about 35 feet, leading to the straight through, front to back room alignment. See:
Shotgun House

There are many of these houses in the lower income areas that were flooded; they are a prime worry of the preservationists. One would hope that their effective, low-cost wood design will persist.

The website given above shows some prime examples.