The nearby cluster of galaxies A2256 (z~0.06) is one of the rare
 clusters having an extented radio halo - a phenomenon which is
 not understood yet. This remarkable feature has sharp boundaries,
 covers an area of ~ 50 sq.arcmin. and has a total flux of 245 mJy
 at 1.44 GHz.
 A ROSAT pointing revealed a double peak of X-ray emission, sugges-
 ting the merging between a cluster and a group of galaxies, a
 possibility which is in agreement with the distribution of the
 galaxy velocities. Subsequent deeper ROSAT observations provided
 a 2-D  temperature map, clearly showing temperature gradients
 and thus, assessing the merging hypothesis. In this cenario, the
 radio halo find a natural explaination in terms of cosmic
 ray acceleration at the merging front.
 12 IRAS sources are found in the field of A2256; 7 of them
 are associated with discrete radio sources belonging to
 the cluster.
 A2256 is a unique case of a "halo" cluster studied in such detail
 in three wavelengths for which a coherent picture is now possible.
 Evidences found in favor of a turbulent intra-cluster medium are compelling
 arguments to perform ISO observations in order to investigate the peculiar
 star formation activity, which is undoubitably triggered by the violent
 interactions taking place in the merging processes.