We first visited Boise on Labor Day weekend in 2017 and from that first trip I was dreaming up my perfect route from the city to the summit.
After years of other runs getting in the way, I finally prioritized this silly challenge, and "The Capitol is Bogus" was the end result.
It starts with a *ding* of the Liberty Bell replica on the Statehouse steps and concludes with a sit down on the rock pile at the summit of Shafer Butte. It's 20 miles long with 6,000 feet of elevation gain and being point-to-point, it requires some fun logistics to get yourself back to town. (I recommend running it with friends!)
Running up Lucky Peak to start is a great way to put yourself in the box for the next few hours, I'd highly recommend starting this one in Avimor and heading southeast.
That being said, it's mostly dirt roads and non-technical, but it's not all intuitive, so make sure you save the route ahead of time to guide you. Also, it's all not all technically 'public'... so do with that what you will. I do not advocate crossing private land, if it's posted no trespassing.
The route is somewhere between 35-40 miles depending on how you do it, with over 7'k of vertical gain, and only about 20% of it is actually fun to run. But it looks super impressive on Strava, so you should definitely do it.