NEW YORK CITY—Modular construction often connotes prefabricated single standing homes or an idea useful for remote areas with labor shortages. But Isaac-Daniel Astrachan, the executive architect from Stephen B. Jacobs Group Architects and Planners which designed the world's largest standing modular construction hotel, citizenM at 189 Bowery, says it's only a matter of time before its popularity catches on in urban areas, especially those needing affordable housing.