It’s a marked US Highway. The claim is 318 turns in 11 miles. I drove it three weeks ago but I didn’t keep count.
Kegon Waterfall, Nikko National Park, Japan. ~100M plunge. You buy the medal for 500 yen and then a machine counterstamps it with your name (or whatever you type) and the date (for another 300 yen). Pricey and touristy, but I couldn't resist.