The Collaborative International Dictionary of English v.0.48:

Amber room \Am"ber room\
   A room formerly in the Czar's Summer Palace in Russia, which
   was richly decorated with walls and fixtures made from amber.
   The amber was removed by occupying German troops during the
   Second World War and has, as of 1997, never been recovered.
   The room is being recreated from old photographs by Russian
   artisans.
   [PJC]