A modular light fixture has interchangeable assemblies for a top-mount configuration and a bottom-mount configuration. The cage, lens, and roof are the assemblies that can all be interchanged between the different mounting configurations. Each one of these assemblies has the same geometrical shape in the top-mount configuration and in the bottom-mount configuration. The cage has an upper collar, a lower collar, and side rails that connect the collars. The lens is a single-piece shell that is formed in either a prismatic shape or a cylindrical shape. The roof slopes downward from a center section to an outer section. The top-mount bracket assembly for the top-mount configuration is a single-piece injection-mold plastic part which can be produced with an arm extending from a wall panel and without any finial.