lair raided, how to protect?

my lair was raided recently and all my items stolen.. granted, it was more or less out in the open and i didn't lose anything important, just a bunch of things i liked and had collected.

how do you protect your lair? aside from putting it in a more secretive location..

You can get a lair guardian which will deter burglars. A wilful thief can still make their way in but most probably wouldn't feel that need.