  The very inner structure of massive young stellar objects (YSOs) is difficult
to trace. With conventional observational methods we identify structures still
several hundreds of AU in size. However, the (proto-)stellar growth takes place
at the innermost regions (<100 AU) where the actual mass transfer onto the
forming high-mass star occurs. We present results from our programme toward
massive YSOs at the VLTI, utilising the two-element interferometer MIDI. To
date, we observed 10 well-known massive YSOs down to scales of 20 mas
(typically corresponding to 20 - 40 AU for our targets) in the 8-13 micron
region. We clearly resolve these objects which results in low visibilities and
sizes in the order of 30-50 mas. For two objects, we show results of our
modelling. We demonstrate that the MIDI data can reveal decisive structure
information for massive YSOs. They are often pivotal in order to resolve
ambiguities still immanent in model parameters derived from sole SED fitting.
