The article is worth reading if you aren't familiar (I wasn't).

It's the Anton Anderson Memorial Tunnel in Whittier, Alaska. It was built during WWII and opened up Anchorage to overland travel. It seems almost primitive compared to interstate hwy tunnels.

Isn't Whittier (the town that the tunnel leads to) also interesting in its own right? IIRC, the entire town is in one big building; and in winter everyone is basically shut in. There's a school inside, grocery store, post office, police, fire, etc. etc. Going from memory here.