Monks Mound is the largest structure and central focus of the city: a massive platform mound with four terraces, 10 stories tall, it is the largest man-made earthen mound north of Mexico. Facing south, it is high, long, wide and covers . It contains about of earth. The mound was built higher and wider over the course of several centuries, through as many as 10 separate construction episodes, as the mound was built taller and the terraces and apron were added.