One of your first stops should be Marshall Visitors Center. Here, you'll be able to orient yourself and get some great tips before you begin exploring.
You'll have sightseeing choices galore when visiting Marshall. Marshall Visitors Center is a great place to start here, but there are many other worthwhile spots to explore. Lincoln Trail State Park, Marshall Public Library, and Clark County Hisorical Society and Museum are near the tourist information center and will round out your day nicely.