  Einstein's theory of General Relativity is one of the pillars of modern
physics. For decades, the theory has been mainly tested in the weak field
regime with experiments in the Solar System and observations of binary pulsars.
Thanks to a new generation of observational facilities, the past 5 years have
seen remarkable changes in this field and there are now numerous efforts for
testing General Relativity in the strong field regime with black holes and
neutron stars using different techniques. Here I will review the work of my
group at Fudan University devoted to test General Relativity with black hole
X-ray data.
