In 1981, workers on a new building site in the heart of the old town of Carouge in Geneva discovered under a thick layer of clay a number of large beams identified as silver fir; these measured up to 10 meters in length. There were also several oak posts. Together they formed the remains of what appears to have been a Roman fortification. Dendrochronology dated the beams to the middle of the second century AD. The conservation method of choice was controlled air drying. Without any pretreatment the beams were placed within a plastic tent in which the relative humidity could be controlled by opening and closing small windows. Core samples were taken to determine the water content-profile over the cross-sections of the beams. These measurements were used to adjust the drying rate to allow water from the inner part of the beam to diffuse slowly to the surface. Over a two-year period, the water content dropped to 10%, shrinkage was minimal, and the wood regained most of its original strength. The same method is now being used on the oak posts.