A Lair

1. A place inhabited by a wild animal, often a cave or a hole in the ground.
2. A shed or shelter for domestic animals.
3. (figuratively) A place inhabited by a criminal or criminals, a superhero or a supervillain; a refuge, retreat, haven or hideaway.
4. (Britain dialectal) A bed or resting place.
5. (Scotland) A grave; a cemetery plot. [from c. 1420]

Synonyms

• (of an animal): burrow (of some smaller mammals), den (of a lion or tiger)
• (of a criminal): den, hide-out