A combination of preserved buildings, museums and research centers all rolled into one, The Historic New Orleans Collection is a good introduction to the history of the city. The complex is anchored by its Royal St campus, which presents a series of regularly rotating exhibits and occasional temporary exhibits. Some of the artifacts on display include an original Jazz Fest poster, transfer documents of the Louisiana Purchase, and utterly disturbing slave advertisements.
The Williams family was always considered eccentric, and the museum's Williams Residence – purchased by the family in 1938, in what was then considered a dowdy neighborhood – is stuffed full of art and furniture collected on the Williams' world travels. As entertaining as the tour is, even better is the introductory video, although it glosses over the source of their fortune (ie harvesting out the old-growth cypress of the Louisiana wetlands).