Massive stars are mostly found in massive clusters, and in  proximity of 
giant HII regions. Thereby, their location is a successful way to select 
some interesting massive clusters, a natural laboratory for studying stellar 
evolution, and to map the large scale structure of the Milky Way. The numbers
and spatial distributions of massive stars are quite uncertain, mainly 
due to our poor knowledge on distances and dust extinction. 
I will present a small review on the current census of massive stars/and 
clusters in the Milky Way, show you some of the work I have been doing on 
clusters, and discuss a set of new criteria for finding them. Available 
new photometric  data from large surveys of the Galactic plane (e.g. 2MASS, 
UKIDSS, VISTA, MSX, and GLIMPSE) allow for new types of searches. These 
stellar color criteria are very suitable for constructing a 3D view of the 
inner young stellar population of the Milky Way. On a very large scale, 
such stars represent a useful calibraton for resolved stars that ELT will 
observe in far distant galaxies.