The Camposanto Monumentale, a 13th century cemetery located alongside the Leaning Tower, hosts important frescoes painted by, amongst others, Benozzo Gozzoli, Taddeo Gaddi, Spinello Aretino and Buonamico Buffalmacco. During the Second World War an incendiary bomb exploded in the cemetery, burning the wood and melting the lead of the roof. Since then the paintings have been almost constantly under restoration. The current situation is that most of the paintings have been cleaned and transferred onto an inert glass resin support, and only four beautiful and important paintings still need to be restored: <i>The Triumph of Death</i>, <i>Universal Judgment</i>, <i>Hell</i> and <i>Stories of Holy Fathers</i>, all attributed to the Master of <i>The Triumph of Death</i>. This article outlines some aspects of the conservation project developed in collaboration with several national and international institutions. The restoration protocols adopted till now are described. Moreover the chemical characterisation of organic materials present on the paint surfaces has been performed using Py-GC-MS analytical procedure, permitting to choose a cleaning methodology based both on solvent and laser cleaning.