Here are some real-world suggestions, either as inspirations or … well, heck, why not steal / take over one as your very own? You are, after all, a super-villain.
6 Real Locations That Are Clearly Secret Supervillain Lairs | Cracked.com
We live in a world of strange structures and eldritch locations that are seemingly normal, but are clearly cartoonish supervillain lairs.
Awesome !!!