Illinois, worth the detour.

Outdoors

A National Natural Landmark of limestone cliffs and caves rising straight out of the river at the mouth of the Apple River -- three separate developed overlooks, including the aptly named Lookout Point, let you pick your view without committing to a serious hike.

History

A 2002 reconstruction of the 1846 original stands on the same high bluff the first temple did, facing west over a wide bend in the Mississippi -- Nauvoo was briefly one of the largest cities in Illinois before its Mormon population was driven out in 1846, and the temple grounds are free to walk even without touring inside.

History

A winged, antlered, man-devouring creature painted on a limestone bluff -- Marquette and Joliet recorded seeing the original pictograph in 1673, and this 48-by-22-foot 20th-century repainting keeps the legend staring down at Great River Road traffic today, several hundred yards upstream from where the original stood.

History

4.4 million gallons of water merge here every second -- the Ohio and Mississippi visibly run side by side in different colors before mixing, viewable from a 1960s observation tower at the literal southern tip of Illinois, the lowest point in the state at 279 feet.

Nature

An elevated platform four miles north of Fulton puts you directly over a working lock chamber -- this is one of the Army Corps of Engineers' flagship winter eagle-watch sites on the whole river, with flocks of bald eagles, white pelicans, and cormorants converging on the ice-free tailwater.

Nature

The oldest and largest lock on the whole Upper Mississippi sits on an active U.S. Army arsenal island -- the visitor center's observation deck watches barges lock through 38 vertical feet while eagles work the open tailwater every winter, a Quad Cities institution drawing 60,000+ visitors a year.