Albert de Gondi, Duke of Retz, had a grotto built in 1582 in the gardens of his château de Noisy (now in Bailly near Saint-Germain-en-Laye). Destroyed in 1732, it was known for its engraved views and long description. Its location, which did not subsequently change, is situated in a forest area, which made it possible to organise a first archaeological excavation in 2017. Among the main discoveries were a section of the decoration still in place, consisting of shells and rockeries, mouldings and decorative fragments, vaults in gilded and painted plaster, carved stones, and paving or hydraulic elements. The analysis of the remains, which is in progress, and the continuation of the excavations, planned for 2019, will make it possible to determine the origin of the materials and the methods of their construction in order to establish the links between the Grotto of Noisy and the Florentine origin of its commissioner and of its decorator.