This will probably be a short thread, on vaults (not their doors) that are interesting or unusual. Much of the time a vault is pretty plain, being simply a room with strong walls. Visually, attention is drawn to the impressive doors and makers have spent some time on their appearance.
In very old times a vault was built as a box right out in the open. Here’s an example from 1912 in Adrian, Michigan:

These seem to have gone out of style rather quickly, though they do have the advantage of being able to view up to five sides to spot breakin attempts. What’s interesting is a more contemporary example of a vault that sticks out into the bank’s main space. This is the Jaindl Building in Allentown, Pennsylvania:

This appears to be a Diebold door. Aside from intruding into the main space, it’s also at a 45-degree angle.
Another interesting vault was (is?) in Cheektowaga, New York. The vault is cylindrical and half of it is outside the building itself. I have not been able to find where this was, so I don’t know if it still exists. This is from an article in the Mosler Messenger, April/May/June 1958:

A similar concept was in Lynwood, California, with a round-door, round vault:

Note that the doorstop just sticks up out of the floor by itself (rather than being next to a wall) and presents a bit of a trip hazard when the door is closed. This building is gone.
Back in time (though it still exists), one of our favorite French vaults has been discussed for its impressive Fichet door. But if this old print is accurate, the vault itself is impressive at least for its size:

If there are other impressive/unusual vaults, feel free to add them!