If you want to get a thorough understanding of New Orleans' history, I can really recommend this tour. Our guide Suzanne was great and really made us understand the development of the city with its both French and Spanish background. If I got it right, the guides are working for tips, and the fee you are paying for the tour instead supports the Louisiana State Museum, which is a good thing itself. You also get a free entrance ticket to the Cabildo, a former government building which is now a museum about NOLA's history, located at Jackson's square. Just note that it is a 2 hours long walking tour, which can be a bit demanding if you are not well prepared.