VLT interferometer: preparation for first fringes

With its `first fringe' milestone planned within a year the VLT Interferometer (VLTI) has entered a phase where it becomes possible to have a preliminary validation of its system performance by combining results of tests obtained at sub-system level. This is also the time for a careful planning of integration and commissioning activities. After an overview of the system approach used in the course of the VLTI project to predict and control the system performance, we present the results of the last crucial tests done on the thermal behavior of the underground, air-filled Delay Line Tunnel. These results have enabled to validate the early assumptions made on the effects of internal air turbulence (so called `internal seeing'). Finally, the last section presents the basic approach to the integration and commissioning of the VLTI to start this year at Paranal.