County, District
The buddy building is in the next county. If it was in your county then it wouldn't be a buddy, it would be a neighbor. You're aware of this building, but they aren't that close, so they're just a buddy.
Imagine looking at a map of your county and the surrounding ones. All of the buildings in the counties next to yours are buddy buildings!
ぐん
こおり
None
Your county is everything you can reach when shooting a gun (ぐん). If the bullet can't reach a building you know, it's a buddy building in another county.
Imagine taking out a gun and shooting in a random direction. When you find where the bullet landed, you know that's the county line. Though if it gets stuck in a building or a person it doesn't count. You'll have to try again.