Military Reserve in the Foothills is 460 acres and is basically adjacent to downtown and connects over 130 miles of mountain biking and hiking trails known as the Ridge to Rivers Trail System to the Boise River Greenbelt.
Here are a few photos, more will be in the photo thread I will be posting in the city photo forum.
Looking down the Gulch which has a creek. Fort Boise and downtown are close by, to the right of this view.
This is a sweet mountain biking trail