A prototype portable tomographic system for microwave imaging is presented in this paper as non-invasive monitoring to preserve cultural heritage worN of art. Initial simulations of the system configuration have been carried out to validate the system architecture. The most significative outputs of these simulations are presented and discussed in the paper. Hence, a first lab microwave tomographic set-up has been developed and tested. The outcomes of this preliminary experiments have driven the development of an optimized portable device for in-situ measurements. A custom-made 3D-printed structure has been built to support the antenna elements of the systems and enclose the target being tested. Transmission measurements between pairs of antennas have been acquired through a vector networN analyzer connected to a modular switching matrix, and the data generated have been inverted by an …