As the crow flies I'm pretty sure Wildcat Falls Conservation area is only a couple miles away from my office in Merrimack New Hampshire, but getting there always seems a little complicated. The main parking area is a 12 minute drive away, and that's assuming a lack of traffic or traffic lights. But when I do manage to go I'm always impressed by this little conservation area.
Location: Merrimack, New Hampshire
Parking: Main parking area is at the end of Currier Rd (on the other side of the highway from the high school). I've also parked in the turn around at W Chamberlain Rd and taken the trail under the highway, over the bridge and back under the highway.
Main attraction: A couple pretty waterfalls and a (I imagine) a swimming hole. The waterfalls are relatively small, but pleasant to look at. We don't have a lot of waterfalls in Southern New Hampshire, so it's nice to have one nearby.
The rocks down by the river make for some fun selfies too.
The trails include about 87 acres that belong to the town of Merrimack and some acreage that belongs to the NH DOT. Some parts of the trail give you a great view of the traffic conditions on Everett Turnpike.
Trails: The trails in the area are easy and smooth. You do find areas with roots and rocks, but it's remarkably not very erroded. There's a total of 2.5 miles of official trails in the park, but there are some additional spurs which allow for longer wanders in the conservation area. If you want to explore more, there's trails that lead under the highway to a pedestrian bridge downstream and to an unoffical trail area behind the high school (at least I've never found a map of this area).
While it's a small area, I think it would be a wonderful place for beginner trail runners to practice while still remaining relatively close to the safety of the car.
Here's a little video of a few of the trails I visited and a view of the waterfalls.