The "chimney" as you call it is a 30' diameter 80' tall cement silo.
The "swimming pool" is a water trough for the cattle that used to live in the barn (and ate the silage that was stored in the silo).
Inside.
It is over 120' long, by about 80 or 90 feet wide. Probably not much bigger than mellowdave's barn, but the perspective of that first pic is pretty good. :thumbup:
More pictures can be found here.