Pretty much as the question states, any other description can be rendered yourself by checking out the image I attached. Thank you for your input.
It didn't come from the mint that way, so not an error coin. Someone had a little too much free time and took a grinder to it.
The reverse of the 2004 was either the "Peace Medal" or the "Keelboat". In any case, your coin looks like PMD. Chris
I also have a nickel missing the building and word. It could be that someone had free time, but I see there is another nickel like mine. The odd thing about the building missing is that it has a precise outline of the building.
Coins are minted in a very high speed process. The odds of a circular object falling into a perfectly symmetrical spot on the reverse while striking is almost zero. It's usually damage, like the photo in the OP someone took a tool/machine and ground off that area.
Not odd at all. It takes some skill with a grinder to remove only the building w/o slipping. It would take mad skills with a grinder to remove down to a flat field.