Constantine of Liechtenstein, the youngest son of the sovereign prince, dies at 51. Born in Vaduz Castle, he graduated in law from Paris Lodron University in Salzburg in 1997. For the time being, the Royal House has not provided further details. If rumours are true, he would have become the brother-in-law of Felipe VI (55), since his sister Tatiana was one of his girlfriends in 1995. In fact, Hans Adam II is the richest sovereign in Europe with a fortune of $7.200 billion, according to the latest Forbes list.