Michael Jackson Insane Interior Design:

Michael Jackson spent more than $700,000 on all sorts of flamboyantly bizarre furniture before he died -- but now, it could be yours ... if the price is right.

TMZ has learned MJ ordered the incredibly unique items for a London mansion he was supposed to live in during the run of his "This Is It" tour ... but he died before the Italian furniture maker -- Colombostile -- could deliver the goods.

Colombostile tells us they gave the $700,000 back to Katherine Jackson and plans to auction the items off in the near future.

Among the items -- lavish sofas, a crystal-encrusted chair, a desk with a secret compartment and much more -- check out the gallery for more details. We're told Jacko bought one of the chairs specifically for his friend Elizabeth Taylor to sit in when she came to visit.

There's also a seashell-studded chair that was intended for MJ's "Little Mermaid" room -- we're guessing it was for his daughter Paris, but then again, ya never know...