  We report the detection of diffuse radio emission which might be connected to
a large-scale filament of the cosmic web covering a 8deg x 8deg area in the
sky, likely associated with a z~0.1 over-density traced by nine massive galaxy
clusters. In this work, we present radio observations of this region taken with
the Sardinia Radio Telescope. Two of the clusters in the field host a powerful
radio halo sustained by violent ongoing mergers and provide direct proof of
intra-cluster magnetic fields. In order to investigate the presence of
large-scale diffuse radio synchrotron emission in and beyond the galaxy
clusters in this complex system, we combined the data taken at 1.4 GHz obtained
with the Sardinia Radio Telescope with higher resolution data taken with the
NRAO VLA Sky Survey. We found 28 candidate new sources with a size larger and
X-ray emission fainter than known diffuse large-scale synchrotron cluster
sources for a given radio power. This new population is potentially the tip of
the iceberg of a class of diffuse large-scale synchrotron sources associated
with the filaments of the cosmic web. In addition, we found in the field a
candidate new giant radio galaxy.
