I have several friends who have squatted abandoned buildings in Europe. I have other friends who live in otherwise abandoned buildings under agreement with the owner to prevent squatters breaking in to the building. When I moved into my house several years back it looked abandoned (because it had been before buying it), and when I invited friends over for the first time some assumed I was squatting there upon arrival. Squatting is really not an unusual thing. Squatters aren't squatting in order to claim ownership. Often they're students looking for a cheap place to stay.