‘Silhas’ are these ancient structures consisting of a small wall of stones, usually circular, and have the function of protecting the cork beehives from the reach of animals, both domestic and wild. They have been used since the middle ages, a time when there were still bears in the region, which led to them becoming known as ‘silhas dos ursos’ or bear defences, since at that time this was the main threat. Along the route it is possible to see various examples of these structures, an indication of how important honey production has been in the region over many generations.