Recently, we stayed at a B&B in Mackinaw City, Michigan (USA). We were having breakfast with a couple from northern Illinois. Later in the week, they were planning to go to Traverse City and driving the Lake Michigan coastline south on their way home. Since they weren't familiar with the Emmet County area, they asked us if there was something they "must see". So, we gave the obvious answer - "you should drive M-119".
In 2003, M-119 was officially designated a state Scenic Heritage Road (aka Pure Michigan Byway). According to Wikipedia, this designation is given to "a scenic, recreational, or historic route that is representative of Michigan's natural and cultural heritage".
I didn't count them but one source reports there are 137 curves along this 20 mile stretch of road from Harbor Springs to Cross Village.
What makes this scenic drive different? Well ...