Fort Harrison State Park occupies land that was once part of an Army base. It comprises about 1,700 acres, though a good chunk of that is taken by a golf course. Fall Creek, which drains a large area of Marion County, runs in a generally southwestern direction through the park, at one point being joined by Lawrence Creek, which comes in from the south. There are large grassy areas with playgrounds and shelter houses, along with a good number of structures left over from the Army days, but the park also has four nature preserves that between them protect more than 600 acres.
Two of the preserves are off-limits to the public: Chinquapin Nature Preserve (115 acres) which occupies most of the northeastern portion of the park, and Bluffs of Fall Creek Nature Preserve (135 acres), which lies north of Fall Creek. The other two preserves are open to the public and have trails that offer ready access.
Warbler Woods Nature Preserve (135 acres) lies between Fall Creek and the golf course. It is home to the Fall Creek Trail, which starts near Delaware Lake and shadows the Creek. The paved, multi-use Harrison Trace Trail loops east from the Delaware Lake area, approaching the eastern property boundary before returning. My favorite trail is the Camp Creek Trail, another loop that lies within the Harrison Trace Trail and meanders along the short bluffs that overlook a small creek. The Lawrence Creek Nature Preserve is in the western part of the park and features the multi-use Lawrence Creek Trail, much favored by local mountain bikers. It has two access points and consists of a large loop with small side loop, and plenty of mud in wet weather.