  We report the results of a new large scale survey of the Orion-Monoceros
complex of molecular clouds made in the J = 1->0 line of CO with the
Harvard-Smithsonian 1.2m millimetre-wave telescope. The survey consists of
52,288 uniformly spaced spectra that cover an area of 432 square degrees on the
sky and is the most sensitive large-scale survey of the region to date.
Distances to the constituent molecular clouds of the complex, estimated from an
analysis of foreground and background stars, have provided information on the
three dimensional structure of the entire complex.
