Let $S$ be a Shimura surface i.e. a Shimura variety with $dimS=2$. Does $S$ necessarily contain a Shimura curve? I know that probably the answer is No, but do not have an explicit example. What is the best example of such a surface?

A trick: for a totally real abelian cubic number field $k$, let $B$ be a quaternion algebra over $k$ that is split at exactly two of the real places of $k$. The associated Shimura variety is twodimensional, but does not contain any natural Shimura curve. (But I do not know how to exclude the possibility of "unnatural" imbeddings...) 

