  Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and
$^{nat}$Pb nuclei has been measured with a tagged photon beam with energies
between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA
accelerator with the combined setup of the Crystal Barrel and TAPS
calorimeters. It aimed at the in-medium properties of the S$_{11}$(1535)
nucleon resonance and the study of the absorption properties of nuclear matter
for $\eta$ mesons. Careful consideration was given to contributions from
$\eta\pi$ final states and secondary production mechanisms of $\eta$-mesons
e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of
the mass number scaling shows that the nuclear absorption cross section
$\sigma_{N\eta}$ for $\eta$ mesons is constant over a wide range of the $\eta$
momentum. The comparison of the excitation functions to data off the deuteron
and to calculations in the framework of a BUU-model show no unexplained
in-medium modifications of the S$_{11}$(1535).
