Massive molecular complexes are the locations for the (present) birth of massive stars. An effort for getting a new census of molecular complexes at intermediate galactic distances has been made since 2000, mostly based on large galactic distance extinction maps.
This new census is the base for the "3kpc opportunity" invoqued for the HOBYS program by Motte, Bontemps, Zavagno et al. under the behave of the Herschel/SPIRE consortium (Griffin et al.).
Among the massive molecular complexes at less than 3 kpc, Cygnus X is very special, and pops out as one of the most extreme molecular complexes of the whole Galaxy. Since 2000, we have an intense activity of research toward this complex in order to investigate the origin of high-mass stars and rich clusters inside this exceptional region which is only at 1.7 kpc from Earth. The large collaborative effort comprises (1) systematic surveys for the earliest phases with the IRAM instruments (see Motte et al. 2007) and with Herschel (HOBYS); (2) large scale molecular line surveys (see Schneider et al. 2006; and the KOSMA Cygnus X page); (3) stellar population and cluster investigations thanks to infrared surveys such as the Cygnus X Spitzer Legacy Survey (Hora et al.).