More than 200 American Indian mounds are preserved here in one of the most picturesque sections of the Upper Mississippi River Valley. Many Americans, especially the Monument's 20 culturally associated American Indian tribes, consider the mounds sacred. A visit offers opportunities to contemplate the meanings of the mounds and the people who built them. All four seasons are represented in this area, with summer temperatures in the upper 80s with higher heat indexes due to humidity and winter daytime highs in the 20s. Temperatures are in degrees Fahrenheit.