The forest of Lailias, the enchanting green lung of Serres at 25 km from the city, is in the western part of the Vrontos mountain range. A forest paradise, with beeches and pines, which starts at an altitude of 700 meters and ends at the highest peak, Ali-Baba, at 1,850 meters.
In Lailias, the tall trees, the steep ravines, the steep and huge rocks, and the alluring seductive location, attract nature lovers all year round. In winter the white, alpine landscape, with the ski center of Lailias attracts ski lovers, in summer it is painted green and cools visitors with its crystal-clear air.
The visitor of the forest of Lailias is impressed by the rich flora (hundreds of plant species, some rare) and its fauna (mammals, birds, reptiles, amphibians). The rocks of Lailias are suitable for climbing, while the forest paths are suitable for hiking, mountain biking, cross-country skiing, and 4 × 4 ridings. One of the picturesque paths of Lailias leads to a huge monolith, the so-called "Katiga Rock". According to local tradition, the young woman Katiga in question committed suicide during the Turkish occupation by falling from the rock of the same name into the deep ravine of the area.
Within the forest complex of Lailias, at an altitude of 1,470 meters, there is a declared monument of nature, the so-called Sfagnonas of Lailias. It is a swampy area, with rare species of Greek flora, which is of paleobotanical interest.