Boonville's sights are mostly clustered along a few blocks of the old downtown above the river, with a handful of historic houses and one outsized Civil War battlefield on the edge of town. It's a half-day place — pick a couple of the historic sites, walk the cobblestone street down to the river, and you've seen the best of it. The Katy Trail and the riverboat casino give you reasons to linger if you want them.