  If we live in the vicinity of the hypothesized Great Attractor, the age of
the universe as inferred from the local expansion rate can be off by three per
cent. We study the effect that living inside or near a massive overdensity has
on cosmological parameters induced from observations of supernovae, the Hubble
parameter and the Cosmic Microwave Background. We compare the results to those
for an observer in a perfectly homogeneous LCDM universe. We find that for
instance the inferred value for the global Hubble parameter changes by around
three per cent if we happen to live inside a massive overdensity such as the
hypothesized Great Attractor. Taking into account the effect of such structures
on our perception of the universe makes cosmology perhaps less precise, but
more accurate.
