The Youngest Globular Clusters
  It is likely that all stars are born in clusters, but most clusters are not
bound and disperse. None of the many protoclusters in our Galaxy are likely to
develop into long-lived bound clusters. The Super Star Clusters (SSCs) seen in
starburst galaxies are more massive and compact and have better chances of
survival. The birth and early development of SSCs takes place deep in molecular
clouds, and during this crucial stage the embedded clusters are invisible to
optical or UV observations but are studied via the radio-infared supernebulae
(RISN) they excite. We review observations of embedded clusters and identify
RISN within 10 Mpc whose exciting clusters have a million solar masses or more
in volumes of a few cubic parsecs and which are likely to not only survive as
bound clusters, but to evolve into objects as massive and compact as Galactic
globulars. These clusters are distinguished by very high star formation
efficiency eta, at least a factor of 10 higher than the few percent seen in the
Galaxy, probably due to violent disturbances their host galaxies have
undergone. We review recent observations of the kinematics of the ionized gas
in RISN showing outflows through low-density channels in the ambient molecular
cloud; this may protect the cloud from feedback by the embedded HII region.
