  This is an article commissioned by the Spanish Physics Magazine ("Revista
Espa\~nola de F\'isica") for the Centennial Anniversary of the discovery of
General Relativity. The article reviews experimental and observational efforts
to test Einstein's theory of General Relativity in a variety of scenarios (from
the Solar System to binary pulsars, from the Sag A* to binary black hole and
neutron star coalescences).
