Liquid Argon Time Projection Chamber (LAr TPC) is currently the most attractive technology for neutrino oscillations studies. Not only LAr TPCs are cost-effective and scalable to multi-ton scales, but they are also excellent calorimeters and are able to 3D reconstruct the tracks of ionising particles arising from neutrinos decay products. Future giant liquid Argon TPCs, at the ten-kiloton level, are now at the design and prototyping stage in the context of the Deep Underground Neutrino Experiment (DUNE). DUNE will comprise four 10 kton LAr TPC modules placed at the Sanford Underground Research Facility (SURF) in South Dakota (USA). Two different technologies will be tested: single phase and dual phase. The dual phase operation allows to amplify and readout the signal offering several advantages over the single phase. The first step towards large scale Dual-Phase LAr TPCs has been the commissioning and operation of a 3x1x1 m3 detector at CERN with 4.2 tons of Argon. The construction, commissioning, performance and first results achieved with this detector will be addressed in this talk.