Built by the elite French Legionnaire forces in 1927 to open a new route to the south, this 200-foot long spiral tunnel between Er-Rich in the north and Erfoud on the edge of the Sahara Desert took a workforce of 3,000 men an astonishing five months to dig through solid rock—using five and a half tons of explosives, 16 hammer compressors, and 11,000 gallons of fuel.

The 50-mile-long canyon that runs alongside was created by the Ziz River cutting a wide path through the Atlas Mountains. It’s a large date-growing region dotted with tiny Berber villages and surreal clusters of palm trees clustered along the dry river bed. The smooth winding road leads to the massive Hassan-Eddakhil lake. Along the way you’ll spy birds of prey, hovering on the updraft, alert for a potential kill. The long flowing corners cut into the edge of the mountainside beats any video game for thrills and the scenery is phenomenal—with a dizzying drop into the Ziz gorge on one side and soaring red cliffs on the other.

Motorcyclists of a certain type will be heartened to know it's a Moroccan custom to give a big wave to other bikers. If they're in a group they're likely to be fellow tourist adventurers, but even solo riders are worth your friendly recognition. On our way to the famous tunnel we ended up making friends with a Fonzie-look-a-like at a gas station—who turned out to be a priest from Texas, riding a customized Harley-Davidson Roadster 300 miles to a friend's place for the weekend. I was amazed at how many Americans we met, all with amazing tales to share.