After the Champ de Mars ghost station the line serves École Militaire and La Tour-Maubourg, curving right and left under the Invalides esplanade and beginning a .04-percent descent under the park tracks and the main tracks of Line 13 to the Invalides station under the Rue de Constantine. At Rue Robert-Esnault-Pelterie, it begins a second .04-percent descent under RER Line C to cross the Seine through a metal tunnel. The line then goes up the Right Bank on a curved, .035-percent grade to the Concorde station.