In order to understand how the most massive stars form, and how they interact with the surrounding Interstellar Medium, we need to study the kinematics and physical properties of gas associated with the star formation process at different scales.    
In this context, I will first focus on the information coming from the inner vicinity of a massive young stellar object (YSO), and then move to the clump scales where multiple star formation takes place. I will discuss the case of the luminous star-forming region G023.01-00.41, where our previous EVN, VLBA, and SMA observations revealed an O-type YSO driving a powerful outflow. Follow up observations with ALMA have now led to the first direct imaging of a disk-jet system around such a massive protostar. Furthermore, EVN, SMA and ALMA polarization observations will trace the magnetic field orientation across 3 orders of magnitude in spatial scales in this system, and will allow us to quantify the magnetic field role with respect to turbulence and gravity. I will then introduce the "CepHeus-A Star formation and proper Motions"
(CHASM) Survey, which targets the second nearest massive star-forming region (after Orion). This large project combines JVLA, SMA, and astrometric VLBA observations, with the aim to reveal the young population of T-Tauri stars around a massive YSO (i.e, Cepheus-A HW2), and will allow us to study the properties of the clump gas around the young stars. I will finally describe the role that SRT can play in this context.