WATCH: 26 years later and Madonna's Sex book is still breaking rules

One thing you can never say about Madonna is that she's boring. Far from it.

During her illustrious pop career, the singer has managed to turn the music industry up side down.

One of her biggest career accomplishments surely must be the release of her singles  Erotica and Justify My Love. Just before releasing the sexually-loaded videos, she famously quipped that she wouldn't take her clothes off for a whole year, “except when I’m in the shower.”

That didn't last long...

In 1992, her Sex book was the most talked about photobook in decades. Madonna teamed up with one of the world’s most successful fashion photographers, Steven Meisel to produce a series of photo essays - each with a different sexual theme. 

To date, it is the the largest-grossing illustrated book of all time.

But according to abebooks.com,  Sex is not actually the rarest or most valuable book by the Queen of Pop. In 2003, Steven Klein and Madonna worked together on a multi media performance art piece which resulted in a limited edition (1 000 copies) hand bound coffee table book entitled  X-STaTIC Pro=CeSS.