Flat-Top Mound and Plaza, also known as Mound H, was a 12-foot-high platform mound paired with an open plaza used by Native peoples for rituals and festivities. People may have watched sermons, speeches, or performances from atop the mound while standing with family and community members in the plaza. Although the specific reasons people gathered there are unknown, Crystal River was a regional gathering place and center of activity for many generations. Archaeologists have found almost no artifacts in the plaza area, leading to the idea that Native peoples swept and kept the space clean after it was used. Decorated pottery fragments found at the site provide clues to religious beliefs and sacred symbols that may have been part of ceremonies held at Crystal River.