Two surveys of high-mass star formation (HMSF) are discussed. One is the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL), using the Atacama Pathfinder Experiment (APEX) 12 metre dish. The other uses the Institut de Radioastronomie Millimetrique (IRAM) Northern Extended Millimetre Array (NOEMA). The value of a representative survey of HMSFRs lies in learning what physical and chemical parameters are shared across a variety of sources. The results of statistically large samples of detected, or non-detected, sources such as that of ATLASGAL provide secure data from which to generalise about the typical star-formation process. The results of smaller but still multi-location studies such as the NOEMA sample give us greater specific details, albeit from a self-selecting sample, which may or may not be typical but that we can certainly say are common, at least until future wider surveys demonstrate error.

The three UCHII regions associated with the G34.26+0.15 high-mass star formation complex in Aquila are described, giving evidence for envelope infall, protostellar outflows, expanding ionized gas, and associated molecular hot core chemistry. The prototypical ‘cometary’ UCHII region ‘C’ in G34.26 is one focus, where the interface between ionized hydrogen (HII) and hot molecular core (HMC) gas is well observed and a rich hot core chemistry both detected and modelled in detail. Uncertainties in CH3CN formation, and the displacement of its peak emission from dust and NH3 peaks, are raised in relation to possible photodissociation in the hot core close to the UCHII-C feature.

Sagittarius (Sgr) B2 is the most massive star-forming region in the Galaxy and the canonical HMSFR with probably the richest source of molecules detected to date, not least in the number of COMs recorded. The consequences of a variable and higher-than-standard cosmic ionization rates in this region close to the Galactic centre are discussed. They are seen to have a complex effect on COMs chemistries, offering both an unusual test bed for chemical evolution theory, while not being conditions representative of more widely observed HMSF cores. The particular case of cyanides and isocyanides stands out, and modelling that uses enhanced but extinction-dependent CR ionization rate brings best agreement between model results and observations. Nonetheless, the modelled column densities of some species are much lower than observed, and the physical structure profile of the regions appears to be responsible.