  The origin of massive stars is a fundamental open issue in modern
astrophysics. Pre-ALMA interferometric studies reveal precursors to early B to
late O type stars with collapsing envelopes of 15-20 M$_\odot$ on 1000-3000 AU
size-scales. To search for more massive envelopes we selected the most massive
nearby young clumps from the ATLASGAL survey to study their protostellar
content with ALMA. Our first results using the intermediate scales revealed by
the ALMA ACA array providing 3-5" angular resolution, corresponding to
$\sim$0.05-0.1 pc size-scales, reveals a sample of compact objects. These
massive dense cores are on average two-times more massive than previous studies
of similar types of objects. We expect that once the full survey is completed,
it will provide a comprehensive view on the origin of the most massive stars.
