The project posed several challenges: a very huge radius of curvature; the impossibility to have an arriving shaft for the TBM (disassembling and removal of the TBM along the tunnel); the proximity to artefacts of huge historical value, and lots of co-activities, which increased the level of difficulty of the work as well. The microtunnels have a length of 138 m and 142 m respectively, internal diameter equal to 2.500 mm, and external diameter equal to 3.000 mm.