Where is Tunnel du Mortier?

Nestled in the Isère department of France, you'll find the abandoned Tunnel du Mortier, a relic sitting pretty at 1,370m. This beauty is located in the Auvergne-Rhône-Alpes region, in the southeastern part of the country. Word on the street is it was first built way back in 1911, then upgraded for the 1968 Winter Olympics in Grenoble.

Sadly, this tunnel closed its doors in 1992 after a massive rockfall wiped out the access road. Picture this: around 20,000 m3 of rock giving way, leaving a seriously unstable zone. Because it wasn't a super critical route, the powers that be decided to let it be. Nowadays, hikers and mountain bikers are the only ones who dare venture through.

So, can you drive through? Technically, the tunnel itself, built wide enough for two lanes, is still there. But the road leading to it? Not so much. The first part is easy enough, but the middle gets seriously dark. Pro tip: avoid looking directly at the light at the other end; it'll mess with your vision. There's a rock slide that has cut off the road further down the climb, so you need to be very careful to cross.

Getting there involves taking the D218, a paved road with some narrow bits. The southeastern side is still drivable up to the tunnel, but the northwestern side? Forget about it—completely collapsed. Expect some steep sections, with gradients hitting up to 12%. Once inside, bring a flashlight, since it’s a long tunnel and completely dark in the middle.