Gallier Hall will undergo a $15 million renovation to shore up its crumbling façade and freshen up its interior, Mayor Mitch Landrieu announced Wednesday.

The city and state will kick in about $10 million to renovate the building’s exterior. Landrieu, meanwhile, has assembled a committee — chaired by his wife, Cheryl Landrieu — to raise $5 million to pay for interior improvements such as restoring chandeliers and renovating restrooms.

“When it’s finished, this ought to be restored to its original luster,” Landrieu said. “It’ll be a symbol for our 300th anniversary (in 2018) of what the city should look like had we done it right the first time.”

The Greek Revival building facing Lafayette Square was designed by prominent architect James Gallier Sr. It was built in the late 1840s and served as New Orleans’ City Hall from 1852 to 1956, when the government moved to the current City Hall at 1300 Perdido St.

Nearly a year ago, a section of stone cornice on the building’s façade broke off and crashed onto the steps below. No one was injured, but the steps were damaged.

A subsequent structural analysis of the granite and limestone building’s exterior found “significant issues” with the stone cornice, Deputy Mayor Cedric Grant told the City Council during budget hearings last year for the Office of Property Management.

Grant, who oversees infrastructure for the city, told the council that water and vegetation had begun eating into the building and it would need a “major, major renovation.”

The front entrance has been blocked off since last summer, but the building still is in use for special events and continues to house the city’s film office.

Landrieu said the fall of the cornice section “woke us up to the need to make major investments in (the building’s) infrastructure.”

Officials will first tackle the front of the building facing St. Charles Avenue, with the goal of having it repaired and reinforced in time for Landrieu to toast the Rex monarch there on Mardi Gras 2016. The viewing stands normally set up for the mayor and city officials in front of Gallier Hall had to be relocated this year.

The exterior of the building will be replaced with Tuckahoe marble, Grant said. Also known as Westchester, Inwood and Kingsbridge marble, Tuckahoe marble is commonly used in the construction of neoclassical-style buildings.

Improvements to the other three sides and the interior will follow. The interior renovation will include restoration of paintings, chandeliers and period furnishings throughout the building. It also will include painting, floor refinishing, a new audio-visual system and upgrades to the restrooms and kitchens.

In addition to Cheryl Landrieu, the Gallier Hall Preservation Committee includes Gayle Benson, Joy Bollinger, Shelia Burns, Collette Creppel, Frances Fayard, Ron Forman, Tony Gelderman, Jennifer Heebe, Sandra Herman, David Kerstein, Anne Redd, Sylvia Scineaux-Richards and Mary Von Kurnatowski.

Legislators approved $10 million in the state’s capital outlay budget — $2.5 million in Priority 2 and $7.5 million in Priority 5 — for the project in the recently ended session.

The last known restoration of the Gallier Hall façade was in 1984, when sandblasting was done to remove an asphalt coating. The building, which is designated as a National Historic Landmark, also underwent improvements in 1949 and 1967, according to the city.