  Given the important role that the galaxy bispectrum has recently acquired in
cosmology and the scale and precision of forthcoming galaxy clustering
observations, it is timely to derive the full expression of the large-scale
bispectrum going beyond approximated treatments which neglect integrated terms
or higher-order bias terms or use the Limber approximation. On cosmological
scales, relativistic effects that arise from observing on the past light-cone
alter the observed galaxy number counts, therefore leaving their imprints on
N-point correlators at all orders. In this paper we compute for the first time
the bispectrum including all general relativistic, local and integrated,
effects at second order, the tracers' bias at second order, geometric effects
as well as the primordial non-Gaussianity contribution. This is timely
considering that future surveys will probe scales comparable to the horizon
where approximations widely used currently may not hold; neglecting these
effects may introduce biases in estimation of cosmological parameters as well
as primordial non-Gaussianity.
