After years of trying to acquire the struggling River Oaks shopping center for redevelopment, Calumet City announced architectural plans Thursday for a complex that incorporates retail, restaurants and housing, despite the city still not owning the property. Gregory Williams, president of the architectural firm Gregory Ramon Design Studio, presented the City Council with visions of a sprawling, modern campus surrounded by a park that would replace sprawling pavement. Williams said working with the city, the firm envisions transforming the 11-acre site into “something that would make it useful 24/7.” “Really a vibrant, thriving development that will help with the community development, economic growth,” Williams said.