  Properties of hadrons and their modification within strongly interacting
matter provide a link between experimental observables and Quantum
Chromodynamics (QCD) in the non-perturbative sector. The sensitivity of various
observables to in-medium modifications of mesons is discussed. The transparency
ratio, comparing the meson yield per nucleon within a nucleus relative to that
on a free nucleon, is related to the in-medium width of the meson. While the
transparency ratio can be determined for any meson lifetime the meson line
shape only contains information on in-medium properties if the meson is so
short-lived that it decays in the medium after production in a nuclear
reaction. Light vector mesons are thus particularly suited for these
investigations. The momentum distribution of mesons produced in a photo-nuclear
reaction as well as the excitation function also show some sensitivity to
different in-medium modification scenarios. As an example, high statistics data
taken at MAMI-C on the photoproduction of \omega\ mesons are presented.
