In this poster I present two recent works [1,2] that aim to enhance our understanding of reconstructing black hole space-times from different type of observations. While gravitational wave detectors like LIGO/Virgo allow to perform black hole spectroscopy of stellar mass black holes, images such as those produced by the Event Horizon Telescope provide information of the shadow from super massive black holes. A theory agnostic approach starting from a parametrized metric is combined with Bayesian analysis to infer possible deviations from simulated quasi-normal modes, as well as the observed size of the shadow of M87*.
 Bayesian Metric Reconstruction with Gravitational Wave Observations, Sebastian H. Völkel and Enrico Barausse, Phys. Rev. D 102, 084025, 2020, https://arxiv.org/abs/2007.02986
 EHT tests of the strong-field regime of General Relativity, Sebastian H. Völkel, Enrico Barausse, Nicola Franchini and Avery E. Broderick, in review, https://arxiv.org/abs/2011.06812