(c) Wilsilver77 | Dreamstime.com
One of the twin Spanish colonial buildings flanking St. Louis Cathedral, this one, on the right, was built on the site of the priests' residence, or presbytere. It served as a courthouse under the Spanish and later under the Americans. It is now a museum showcasing a spectacular collection of Mardi Gras memorabilia. Displays highlight both the little-known and popular traditions associated with New Orleans's most famous festival. "Living with Hurricanes: Katrina and Beyond" is a $7.5 million exhibition exploring the history, science, and powerful human drama of one of nature's most destructive forces. The building's cupola, destroyed by a hurricane in 1915, was restored to match the one atop its twin, the Cabildo. Allow at least an hour to see the exhibits.