The Drift Tube Linac, also called Alvarez linac by the name of the inventor, is a well-established accelerator structure, used for ion acceleration since the '50's. The application of some key inventions as well as the general advance of the technologies (mechanics, RF, vacuum, materials) have continuously improved the DTL performances along the decades. INFN is now committed to complete the construction, installation and commissioning of Drift Tube Linac for the European Spallation Source. An overview of the activities for this project will be given in the seminar. As a consequence of the in-depth study of the DTL principles, some ideas for new applications has been developed. An example is the Alpha-DTL: a DTL based linac for alpha particle accelerator at variable energy.