  Blazars are known for their variability on a wide range of timescales at all
wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales,
especially during flares. With a decade of observations from the Fermi-LAT and
VERITAS, we present an extensive study of the long-term multi-wavelength
radio-to-gamma-ray flux-density variability, with the addition of a couple of
short-time radio-structure and optical polarization observations of the blazar
1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from 100 MeV to
30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the
gamma-ray and optical flux baseline and a linear correlation between these two
bands are observed over the ten-year period. Typical HBL behaviors are
identified in the radio morphology and broadband spectrum of the source. Three
stationary features in the innermost jet are resolved by VLBA at 43.1, 22.2,
and 15.3 GHz. We employ a two-component synchrotron self-Compton model to
describe different flux states of the source, including the epoch during which
an extreme shift in energy of the synchrotron peak frequency from infrared to
soft X-rays is observed.
