At the inner Lindblad resonance in the barred spiral active galaxy NGC1365, we have discovered a number of new sources, compact and bright, which popup at mid-infrared and radio wavelengths, while they are invisible in the optical and near-infrared. Imaging and spectroscopy in the mid-infrared have been collected at the VLT with VISIR, and are used to unveil the nature of such sources. Using several age indicators and two modelling tools (STARBURST and GRASIL), we find that these sources correspond to star clusters at an age of about 7 Myrs, extremely massive, 10^7 Mo, and still embedded in their parent molecular material. This poses a number of key-questions : How could they be so massive ? How is it that at this age they are still embedded in cold material ? What is their lifetime ?