  We explicitly write down the {\it Eisenstein cycles} in the first homology
groups of quotients of the hyperbolic three spaces as linear combinations of
Cremona symbols (a generalization of Manin symbols) for imaginary quadratic
fields. They generate the Eisenstein part of the homology groups. We also study
the Eisenstein part of the cohomology groups. As an application, we find an
asymptotic dimension formula (level aspect) for the cuspidal cohomology groups
of congruence subgroups of the form $\Ga_1(N)$ inside the full {\it Bianchi
groups}.
