  We present the analysis of multi-wavelength observations of seven
extragalactic radio sources, listed as unidentified in the Third Cambridge
Revised Catalog (3CR). X-ray observations, performed during Chandra Cycle 21,
were compared to VLA, WISE and Pan-STARRS observations in the radio, infrared
and optical bands, respectively. All sources in this sample lack a clear
optical counterpart, and are thus missing their redshift and optical
classification. In order to confirm the X-ray and infrared radio counterparts
of core and extended components, here we present for the first time radio maps
obtained manually reducing VLA archival data. As in previous papers on the
Chandra X-ray snapshot campaign, we report X-ray detections of radio cores and
two sources, out of the seven presented here, are found to be members of galaxy
clusters. For these two cluster sources (namely, 3CR 409 and 3CR 454.2), we
derived surface brightness profiles in four directions. For all seven sources,
we measured X-ray intensities of the radio sources and we also performed
standard X-ray spectral analysis for the four sources (namely, 3CR 91, 3CR 390,
3CR 409 and 3CR 428) with the brightest nuclei (more than 400 photons in the
2'' nuclear region). We also detected extended X-ray emission around 3CR 390
and extended X-ray emission associated with the northern jet of 3CR 158. This
paper represents the first attempt to give a multi-wavelength view of the
unidentified radio sources listed in the 3CR catalog.
