A sett or set is a badger's den. It usually consists of a network of tunnels and numerous entrances. The largest setts are spacious enough to accommodate 15 or more animals with up to 300 metres (1,000 ft) of tunnels and as many as 40 openings. Such elaborate setts with extensive tunneling take many years for badgers to complete. One sett in Southern England spreads over an estimated area in excess of 2,000 square metres – precise measurement has not been attempted. Another sett, in north-eastern Germany, has been shown to have been in use for over ten thousand years.
https://en.wikipedia.org/wiki/Sett