I live in the City. I also live along a year round creek that usually floods in the winter. We have all manner of wildlife here. I have already relocated 6 possums, three raccoons and a beaver. Skunk season is just starting.
Sooo, I had to build something strong. I used 1/2" welded wire (1st cousin to hardware cloth I guess). The run is 10x40 and the wire is set in a concrete perimeter and bolted to the fence posts which are also set in concrete. The run is covered in the same wire. The two gates have two latches each with twist-close doohickies through which is placed a carabiner so the raccoons can't figure out how to open them. I'm crossing my fingers that not even a mouse can get inside the girls' castle......except during the day when I leave the gate open while they're out playing, but I don't think it's likely. Food and water is readily available inside the coop, but only water outside. I figure it is less likely to attract varmints; besides, with all the foraging they can do outdoors, feed is probably not a necessity outside.
The girls love it. When I'm home, I let them out in to the rests of the yard while I keep an eye on the sky for this lovely couple (whose babies are now learning to fly).
The run is attached to the henhouse, an 8x8x9 shed.
Enjoying freedom
Maggie, Silver Laced Wyandotte
Mayberry, Silver Laced Wyandotte
MardiGras, Golden Laced Wyandotte
Millie, New Hampshire Red
Marsala, Buff Orpington
Maya, Amaraucana
I think it will pay off to make sure things are secure.