This nest is the largest we’ve seen and it is at least 35 years old, according to Ray Mendez. At this age, it grows very slowly, but has been continuously occupied. The lower photos were taken in November 2011; the upper long before that.
Ray shares that since they are not dependent on one queen, these nests, except for fire, flood, parasites, predators, etc. are just about immortal. Over the years he has enjoyed watching them close the entrance to the nest at night or when attacked by army ants. They just pull the “lips” together and form a seal, and the next day are they back in business.