In an old cemetery I saw the most knarly twisted cool ancient tree -- will try to get a picture. No idea what it is.

Yews are beautiful and slow-growing yet long-lived.
Deodars are magnificent.
A copper beech is slow but if it survives to maturity is awesome, with trunk like huge elephant hide.

A Black Hills Spruce is peppy and amazing.

A grove of Western Red Cedar is beautific.

The eastern redcedar or Juniperus as pineresin would rather us call them tends to look like pretty ancient in maturity. The bark is very attractive. and wrinkley.

Too bad this wrinkley and attractive aren't used in conjunction with one another when talking about people, huh?

Pines and junipers.

I don't know if any of these will grow in MT:

Arizona cypress??... They remind me of Eastern red cedar (juniperus!) so I wonder if they might age well.

Bald cypress? Weeping bald cypress?

Burr oak? (Q. Macrocarpa) They get big and live long. Supposedly grow in Canada.

Weeping ginkos can look gnarly and there is another gingko called "Chi Chi" that gets these strange growths with age... "Ding a ling" also gets growths....the experts here can tell you if they can grow there.

Here is a link that might be useful: gingko varieties

Boxwoods can get that look. Cedrus libani does, too, but they probably wouldn't love Montana.

I saw very old yews in cemetaries at Saxon chruches in England. I don't even like yews, but these truly inspired respect.

Western yew is native to Montana, although it may not grow on your site.

All wonderful suggestions. Thank you. I will do research on them to see if they are suited for my area.

What Zone is Montana?
Arizona Cypress - ok for Arizona, Texas, New Mexico, etc. Waste of time in Montana. Z7-9 tree.
Deodar Cedar - Z6-Z8 tree normally. Same for Atlas Cedar and (I believe)Lebanon Cedar.
I think Eastern Red Cedar would survive, but Z3-5 seems a bit of a stretch even for it. They occasionlly suffer ice damage down here.
The pine and juniper suggestions would seem the best.

Well I did a little research and here's what I came up with: You're right, scotjute, it's too cold here for Deodor Cedar, Arizona Cypress, and Cedrus Libani. But the Western Yew, and Black Hills Spruce would grow just fine...in fact almost everyone already has one in their yard. Although most people cringe at the thought of actually planting a juniper...I rather like some of them, and will incorporate a few of them into my landscape. But again, they are so common here, everyone has one or ten. I definately like the Burr Oak idea...wish they didn't grow so slowly. And I think I'm going to go for the Western Red Cedar, too. A large, un-pruned boxwood might prove interesting...don't those things grow on the moon, also? Still undecided about a Weeping Ginko. Any input?

A Dawn Redwood probably would not survive your climate, but if you let all the lower limbs grow the Dawn Redwood trunk looks like something ancient looking out of Tolkien or some scary fairy tale.

A Ginkgo is a must, if it will grow.

Unless it's a regional peculiarity I doubt everyone there has a western yew in their yard, generally not a common tree in gardens. Maybe you are seeing another species, such as Taxus X media.

If you search www for "trees montana" "montana trees" etc. relevant pages from Extension and other sources will come up. These list trees likely to work out for you, some of those suggested here will not be.

Bur Oaks (Quercus macrocarpa) don't grow as slowly as you might think, particularly if you choose one of the cultivars from a reputable nursery.

Other ancient-looking trees worth considering include Blackjack Oak (Q marilandica), Post Oak (Q. stellata), One-Seed Juniper, Utah Juniper, and Alligator Juniper.

You could try this tree too, if it isn't too tender:

Here is a link that might be useful: Hawthorne

Note that "hawthorn tree" has no 'e'.