  Information about the inner structure of young stellar objects is crucial for
understanding how the central forming stars gain their mass. However,
especially for observations of (usually further away) high-mass young stellar
objects, conventional imaging has limitations in spatial resolution. By means
of mid-infrared interferometry, we can peek deeply into the strongly
extinguished central 100 AU of such objects. Here, we report on new data we
obtained within our programme using MIDI at the VLTI. Shown are preliminary
results on the known outflow sources AFGL 2136 IRS 1 and Mon R2 IRS 3A. In
particular, we describe how quantities like differential phases give additional
geometrical structure information. We demonstrate how the combined
interpretation of single-telescope and interferometric data at different
wavelength regimes can lead to a more complete picture of the nature of such
MYSOs.
