Filmmaker Mani Ratnam's magnum opus 'Ponniyin Selvan I' has managed to enthrall the audience and critics alike ever since it was released on September 30. Based on eminent writer Kalki's literary classic of the same name, the film is enjoying a fantastic run at the box office. After crossing the Rs 300 crore mark worldwide in a week, 'Ponniyin Selvan I' has now entered the Rs 400 crore club worldwide.