The history of the site is simply impressive. Petersburg is the start of modern trench warfare (and provides a contrast to the understanding of earlier trench warfare you can obtain in nearby Yorktown, just 45 miles away "as the crow flies"). This is also one of the best sites we've found in Virginia for African-American Civil War History. Of course, no visit is complete without seeing the famed Dictator mortar, a huge cannon of sorts with about a 2-mile range, incredible for the time. Also not to be missed? A visit to the Crater site, now even more approachable thanks to some resurfacing of the direct path to the tunnel. The Battle of the Crater, part of the 9-month long siege interpreted at the park, will tap your interests in military tactics, spying, infighting, and more. Our sense is it is little studied in most history classrooms, but it is one of the most interesting historic sites within driving distance of Roanoke, Virginia, period--and regular readers know that we have a good frame of reference for our rating.
While you are there, we highly recommend finding the recently-restored Poplar Grove National Cemetery. Much smaller than Arlington, visitors can feel as if you have fully seen this site within a relatively short time. Take time to wander and reflect, and if you read grave markers carefully, you will find soldiers from both the US Civil War and the Spanish American War, interesting placements of Confederate dead in a national cemetery, rows of US Colored Troops who died quite valiantly, and numerous unknown soldiers. There is an interpretive leaflet available from boxes at the site that will help you understand the context of the cemetery.
If you go, start at the Visitors Center and take in the introductory film that plays on the hour and half-hour. Get out and enjoy nature while you visit, which will also afford you a better understanding of what the area's land was like 150 years ago. Good news: It won't be hard to take a walk in the forest on a standard visit. There are two small "hikes" we particularly recommend for families--the path to the Dictator mortar near the visitor's center that also help guests understand the features of the earthwork trenches, and the very accessible (flat) .5-mile trail into the woods at stop three on the driving trail. Consider taking a snack lunch or picnic (there are plenty of picnic tables at driving tour stop four) so that you do not need to leave the site for a break, which may require a bit of driving. If you are combining trips, you are also very near Richmond National Battlefield Park and will even find signs for the park on some of the routes in to Petersburg.