We drive through Iowa to the Effigy Mounds National Monument, a collection of burial mounds preserved along the river. These are the westernmost traces of a people who thrived in this area over 1,000 years ago before vanishing. The park’s visitor center is well done, with a fine exhibit showing off excavated arrowheads, potshards and the like. There is one smallish set of mounds near the center, covered over with greenery and engulfed with trees, looking little more like a hill in the forest than anything else. The other more complex mounds are spread over a vast area – the nearest requires a two-mile walk up a steep promontory. So we enjoy the center, and view a trio of grass-covered mounds next to the center and distant views of the river before driving on.