The millenary history of the city of Maubeuge, from the foundation around 670 of the monastery of Malbodium by the Merovingian aristocrat Aldegonde to the construction of the fortification of Vauban from 1679, is relatively well known thanks to the work of 19th and 20th century historians. However, important areas of shade still remain, especially over the birth and evolution of the medieval town bathed by the Sambre. To illuminate these, only archaeology manages to bring back traces of this past buried deep under the post-war reconstructions. It was not until the 1980s that the first discoveries were made by passionate amateurs, at random from the work carried out in the city centre. Although a rescue excavation was carried out in 1990 at the foot of the old Porte de France (Place de Wattignies) built by Vauban, it was not until the 2000s that the first real preventive archaeological research began. In 2021 and 2022, taking advantage of the expansion of development projects in the heart of the city, the Inrap (Institute for preventive archaeological research) intervened four times in diagnosis at the Place de Wattignies-la-Victoire, at the Clouterie (avenue de France), on the avenue of Europe and on the route of district heating. The results of these two years of research exceed all expectations of archaeologists. On the Place de Wattignies-la-Victoire, a part of a disappeared bastion protecting the former Porte de France was cleared, allowing to explain the construction techniques used by Vauban and his engineers. Within the boundaries of the Clouterie project, valuable data were collected on the medieval layout of the Sambre and on the continued occupation of its banks from the 13th to the 17th century. Among the most significant finds are the remains of a large stone building of the 15th century, a beguinage (14th-17th century) or those, under the old islet of the Provençal, of an unexpected cemetery of the 18th century. On this same site, it was also allowed to study a part of the bastion called «de Sambre», razed and forgotten since the 1930s, but also to follow all the evolution of «fodder stores», an important military sector of the stronghold between the late 17th and late 19th centuries. At the dawn of the start of a major excavation prescribed by the DRAC on the site of the Clouterie, the conference will present the research methods of archaeologists and describe the main discoveries made during the last two years.