Alas, I didn't know the work of Gary Moore well apart from this song, which I only ever knew because of Nightwish's cover. I noticed on YouTube someone saying this is a traditional song that Gary Moore covered. Not so; for info on the traditional song of the same name, you can go here, and the traditional tune can be heard here (it's loud, just so you're warned).
Gary Moore died today at the age of 58.
Here is the original of "Over the Hills and Far Away", which was a big hit back in the 1980s (the decade in which I was apparently living under a rock):
Swedish Viking metal band, Thyrfing, did a pretty good cover that appeared on their album Urkaft.
Actually, now that I am listening to some Thyrfing, I am kinda digging them...I do enjoy Viking metal a lot...
Anyway, here is probably the best known cover, done by Nightwish. I do think this is one of Tuomas's best covers, and Tarja is just completely majestic here. Not a bad video, too, and I think I've been to the place where they filmed this, though my memory of it is a bit foggy since I was very ill when I was travelling in Scandinavia and for some reason, tragically, Finland was the place where my memories are dimmest.