Gallier Hall, Historic city hall in New Orleans, United States.

Gallier Hall is a three-story marble building on St. Charles Avenue at Lafayette Square in the Central Business District, designed by James Gallier Sr. as New Orleans' city hall. Its Neoclassical facade is fronted by two rows of fluted Ionic columns, and it was dedicated on 10 May 1853 after construction began in 1845.

James Gallier Sr. designed Gallier Hall; construction began in 1845 and the building was dedicated on 10 May 1853. It served as New Orleans' city hall for just over a century, through the Civil War, Reconstruction and the era of Governor Huey Long. After the city offices moved to Duncan Plaza in the 1950s, it continued in civic use and was named a National Historic Landmark in 1974.

Gallier Hall keeps its Mardi Gras role: the viewing galleries in front are reserved for Mardi Gras royalty, and parades on the St. Charles route pause there while marching bands perform. On Mardi Gras Day the mayor toasts the kings of the Zulu Social Aid & Pleasure Club and the Rex parade from the hall.

Gallier Hall faces Lafayette Square on St. Charles Avenue in the Central Business District, so it fits easily into a walking route along the avenue. The building now works as a convention and reception hall with the Ty Tracy Theatre inside, and it opens for civic functions such as mayoral inaugurations rather than regular daily visiting.

Gallier Hall's front galleries are reserved for Mardi Gras royalty: parades on the St. Charles route pause before them, marching bands usually perform there, and on Mardi Gras Day the mayor toasts the kings of the Zulu Social Aid & Pleasure Club and of Rex from this spot. The building also houses the Ty Tracy Theatre, named for the late artistic director of the New Orleans Recreation Department theatre, and used by Julie Condy's Crescent City Lights Youth Theatre.