The Luna Lair is where Luna Girl plans her motives to wreak havoc in Tarabiscoville. It is also the home of her moths that help her with her evil schemes. It is shown in "Owlette and the Giving Owl", and mentioned in "Owlette's Feathered Friend."
The lair itself is in the shape of a sphere and has a door that comes down from above for Luna Girl to come out of. It is silver and has the ability to float away. It also has some defense mechanisms, such as a force field to keep intruders away, and an automatic Luna Beam to capture and immobilize those attempting to break in. However, it's unknown what is inside the Luna Lair.