Pulsars — fast-spinning neutron stars — are precision clocks provided by nature. Finding pulsars in the Galactic Centre orbiting Sagittarius A*, the closest supermassive black hole to the Earth, will offer unprecedented opportunities to test general relativity and its alternatives.
K.L. and R.E. acknowledge financial support by the European Research Council for the ERC Synergy Grant BlackHoleCam under contract no. 610058. Fig. 1 is based on a sketch by R.E. The telescope outline is based on a photograph by E. Middelberg.