South of the Fourth Street Bridge in the Arts District, the steel skeleton of a low-rise office building is nearing completion. Chalmers Equity Group, a local real estate firm specializing in industrial properties, broke ground on the four-story structure at 500 S. Santa Fe Avenue this past summer.  At completion, the building will feature 100,000 square feet of office space, 199 parking spaces and a rooftop amenity deck. The project site sits immediately north of the headquarters of Lucky Brand Jeans, which is housed in a similar building modeled after a 1930s train station. Other ongoing projects in the nearby vicinity include the $449-million Sixth Street Viaduct replacement, as well as a proposed 13-story building across Santa Fe Avenue.