Looks like it's a world record. Hornet's nest with a diameter of seven meters was in one of the abandoned houses of San Sebastian de la Gomera (Spain) — it occupied one of the rooms almost completely! This jack is found by police, who arrived, in response to the complaints of neighbors.
Then abnormal nest surveyed experts. They assured that the ordinary wasps would never build such a huge structure. Rather, experts have suggested, this is some kind of migrated, flown to Europe from Africa. Canary Islands separates Morocco from less than a hundred miles on the water.
Apparently, African wasps loved the place where nobody disturbs them and where never rains, so they decided to settle there for ever.