From a float decorated as their ibis-headed Egyptian namesake, tarboosh-topped members of the Krewe of Thoth toss trinkets to happy throngs along St. Charles Avenue in New Orleans. The occasion is Mardi Gras—not a day but a season in this legendary American city. Along with Thoth parade the krewes (social clubs) of Babylon, Isis, and Cleopatra, among others, the last group winding through Algiers, the second-oldest neighborhood in New Orleans, on the west bank of the Mississippi across from the French Quarter.