  The kagome lattice provides a fascinating playground to study geometrical
frustration, topology and strong correlations. The newly-discovered kagome
metals AV$_3$Sb$_5$ (where A can refer to K, Rb, or Cs) exhibit phenomena
including topological band structure, symmetry-breaking charge-density waves
and superconductivity. Nevertheless, the nature of the symmetry breaking in the
charge-density wave phase is not yet clear, despite the fact that it is crucial
in order to understand whether the superconductivity is unconventional. In this
work, we perform scanning birefringence microscopy on all three members of this
family and find that six-fold rotation symmetry is broken at the onset of the
charge-density wave transition in all these compounds. We show that the three
nematic domains are oriented at 120$^\circ$ to each other and propose that
staggered charge-density wave orders with a relative $\pi$ phase shift between
layers is a possibility that can explain these observations. We also perform
magneto-optical Kerr effect and circular dichroism measurements. The onset of
both signals is at the transition temperature, indicating broken time-reversal
symmetry and the existence of the long-sought loop currents in that phase.
