Really, really, really big tree

All right...I do hope I'm putting this in the right place! *blush*

This is more for curiosity's sake, but it would be interesting if I could make it at least semi-realistic for a future story. So while I realize it's doubtful I'll get any scientific answers to something so scientifically impossible, I'd appreciate educated guesses, at least.

The basic premise: In the traditional Ojibwa (Chippewa) worldview, there was an immense white cedar known as the Great Medicine Tree and this thing was so tall that it spanned through the "four realms"--the underworld, the earth we live upon, the sky, and the "sky vault" (which I would assume is the atmosphere, where it ends right before space, however that goes...*is ignorant*). The very top of the tree pokes through the "sky vault" to let in light. Meaning, this is one hugely immense gargantuan tree.

I'm mulling over including this tree in a future story. While there are plenty of fantastic liberties taken (I mean, just think about the idea of this tree and you'll see what I mean...in my story, thunderstorms are caused by giant birds hunting lake serpents, see?), I wondered just how big such a tree would be if it were real.

So...anyone have any idea? It's a white cedar, if that makes any difference. How many miles high would this thing be (from the ground up...I'm guessing there's no way to know how long/deep the roots are?), and, what I'm more interested in knowing, how wide across (diameter) would the trunk be? Is this something that, if you were right next to it, you wouldn't be able to see anything ahead of you but trunk, endlessly from left to right? Would you be able to see any of the branches (immense, to match the tree's height) so high above or would it all be lost in haze? *is curious*

I realize I can just make it all up to suit my story, but I still wanted to know, if possible.

Hm, I'm not sure if I was clear... *blush*

Firstly, I'm not asking about the world's largest trees which really exist...I'm asking about a mythological tree, as if it were in existence.

Secondly, I realize the physical impossibilities of such a tree, so things such as its weight, or how the wind or elements would affect it, don't come into play. The story is mythological, so there's a suspension of disbelief in that there is simply a giant white cedar stretching from the earth to the sky vault. I assume it looks basically like any other white cedar, just really really big. (Not merely tall, but wide to match--imagining that its circumference and height are in the same proportions as an average white cedar, just increased.) Due to it being the "Great Medicine Tree" (a supernatural being), its weight isn't a problem, the hole it pokes through the sky vault isn't ruining the atmosphere or anything, etc.

I was just curious to know how many miles high, for example, this thing would be, if its branches would be visible from the earth's surface, and how great would be the diameter of its trunk if this were physically possible (again, suspending disbelief).

Recall this obviously isn't scientifically based. *blushing again*

I just realized something! My question is more speculative (fantasy/mythology) in nature and I've posted it here, in the research-type forum. I was going to post it in the Science Fact item as that's in the Fantasy area, but saw that that was all for, well, science fact, so I thought this was the appropriate place. Was I in fact incorrect? I notice that most questions here are looking for more factual-type answers whereas mine is speculative, even though I am interested in knowing how tall and wide the thing would be, scientifically speaking. Should I have posted to Fantasy instead? So sorry if I was wrong!