  We report the first experimental demonstration of distillation of quantum
nonlocality, confirming the recent theoretical protocol [\textit{Phys. Rev.
Lett. 102, 120401 (2009)}]. Quantum nonlocality is described by a correlation
box with binary inputs and outputs, and the nonlocal boxes are realized through
appropriate measurements on polarization entangled photon pairs. We demonstrate
that nonlocality is amplified by connecting two nonlocal boxes into a composite
one through local operations and four-photon coincidence measurements.
