Abstract: Ultra-relativistic nuclear collisions at RHIC and LHC provide unprecedented opportunity to study QCD at its heart - structure of the vacuum, breaking of the chiral symmetry and origin of the hadronic mass. The existence of strong EM fields created in heavy ion collisions, the strongest ever experimentally studied, might allow for the first time direct experimental access to the quark interaction with topologically nontrivial gluonic configurations, and study of the
so-called '"local parity violation" in strong interaction. In this talk I review available experimental results related to these phenomena, possible backgrounds that could complicate the interpretation, and future measurements.