The mountain is a volcano, second to last in the Cascade Range. Not only is it a volcano, it is large enough to make its own weather. As you might imagine legends go back forever. The local Native American tribe,.the Klamath, (don't quote me) has their origin story there or the Great Chief landed on the summit or something like that, so it is sacred. People go there to do sweats in pelt tents.
Some say aliens, or someone, built a city inside it. There are weird metaphysical anomolies/phenomena that some have witnessed. And I think they saw Big Foot in those parts back in the 70s.
The town, Weed, is at. the foot before the town of Shasta City and it is the northern border of California Cannabis growing country. The world's premier.
There is plenty on Google.
Here's the Wikipedia: