  We present the cross-section for the production of a Higgs boson at
hadron-colliders at next-to- next-to-next-to-leading order (N3LO) in
perturbative QCD. The calculation is based on a method to perform a series
expansion of the partonic cross-section around the threshold limit to an
arbitrary order. We perform this expansion to sufficiently high order to obtain
the value of the hadronic cross at N3LO in the large top-mass limit. For
renormalisation and factorisation scales equal to half the Higgs mass, the N3LO
corrections are of the order of +2.2%. The total scale variation at N3LO is 3%,
reducing the uncertainty due to missing higher order QCD corrections by a
factor of three.
