A nest created by a mature colony of harvester ants is undeniably spectacular. In a study by the Florida State University, a nest void was filled with a thin slurry of orthodontal plaster poured into the nest entrance. This produced a nearly perfect three-dimensional rendering of the nest’s voids. The hardened cast was excavated and then reassembled to produce the finished cast.
This pic below is one such nest that consisted of 135 chambers and 12 meters of vertical shafts. The top-heavy distribution of chamber area and spacing is typical for the species, as are the helical shafts and the decrease of chamber size with depth.
There are many more pics at the link below, they’re amazing.