I recently accessed the New Orleans Notarial Archives online here.
In February 2009 the archives was facing a looming financial crisis
(but are currently online). The history of the New Orleans Notarial
Archives provides a good overview of this unique system.
In regards to finding property records:
"While there is no comprehensive index to the records, a companion
office to the Notarial Archives, the Register of Conveyances,
maintains party-name indexes to property transfers back to 1827.
The Conveyance indexes are annual, and are divided into "Vendor
(seller)" and "Purchaser." The Conveyance indexes are extremely
useful in locating notaries – essential data in accessing notarial records
created before 1970."
Below are two examples of items in the Notarial Archives:
April 21st - May 31st 1798
Pages 1 - 270 Inc.
vs. Estate of Estevan Burnel
re: collection of a debt
10 May 1798
There are also plan book plans, described as architectural drawings of
buildings in New Orleans:
"The drawings were created as legal descriptions and
advertisements of houses, lots and tracts of land offered for
sale at public auction."