Richest king in the world?

It is commonly assumed that King Bhumibol Adulyadej of Thailand is the richest monarch in the world, with a wealth of $30 billion. However, some dispute this, pointing out that the majority of Queen Elizabeth's (and her heir's) holdings, remains a mystery. Her wealth is divided into two. One is a Venetian-style fondo (trust), that is inalienable and must be passed on to her heir, tax-free. The second is her private collection of castles, jewelry, art, stock holdings, bonds and real estate worth about £3 billion. Her fondo trust, managed by a trust and a panel of financial institutions includes over 300 properties, a Royal art collection consisting of over 30,000 items, the Duchy of Cornwall and Lancaster (about 180,000 acres in size), the Crown Jewels, her various landholdings in the United States through proxy companies such as Delta and Pine Land, and much more. The British Parliament is forbidden from revealing the details of the trust' actual wealth, and it is believed to be administered by the Bank of England. Some has estimated the the British monarchy holdings exceeds $100 billion.