Complex sentence: The best known group is the Mound Builders of the Hopewell culture, and today a large number of their burial mounds can be seen near Chillicothe at the Hopewell Culture National Historic Park.
Split into simpler sentences: The best known group is the Mound Builders of the Hopewell tradition. Numerous burial mounds can be seen near Chillicothe at the Hopewell Culture National Historic Park.