NEW ORLEANS, LA - AUGUST 24:  The Mercedes-Benz Superdome stands (Top R) downtown near the abandoned Charity Hospital (Lower L), which was flooded during Hurricane Katrina and never re-opened, on August 24, 2015 in New Orleans, Louisiana. The Superdome site was used as a &#039;shelter of last resort&#039; during Hurricane Katrina. The tenth anniversary of Hurricane Katrina, which killed at least 1836 and is considered the costliest natural disaster in U.S. history, is August 29.  (Photo by Mario Tama/Getty Images)