Abstract: Modular forms are functions with good transformation properties

with respect to the group $SL_2(\Z)$. Modular symbols were introduced by

Birch and Manin to study elliptic curves. A Hilbert modular modular form

is a function with good transformation properties with respect to the

group $SL_2(\Z[\sqrt{d}])$, where $d$ is a (square-free) positive integer.

In this talk will present a geometric construction of a Hilbert modular

symbol.