Is there a specific level range where strongholds can be found?

Question

I'm still a newbie with Minecraft and I have the Xbox 360 version, if that matters.

Anyway, I've been wondering if there's a level range in which strongholds can be found. I know that they don't (or it's really rare?) spawn at the ground-level and that sometimes they're found near/in mineshafts, but...that's all I know.

(Aside from all of this, I'm still trying to get more Ender Pearls to craft Eyes of Ender so I can locate the portal/stronghold in one of my worlds, and this question just came up out of curiosity.)

Answer 1

No, there is no level range that strongholds must spawn at. If you take a look at the page on Minecraft Wiki, you can see that strongholds can spawn on any level in the world except for partially or fully above ground. In other words, they must always be below ground, but apart from that there is no limit.

Answer 2

They are found usually at least 10 blocks down from average ground (y=0). But only at least. Technically it could be either at bedrock level too, which also means it could be found under water, or deep in lava.