In the Estremadura Limestone Massif three different sub-units can be observed from a morphological point of view which correspond to quite high compartments, the Candeeiros Mountains to the west, the Santo Ant�nio Plateau to the south, the S. Mamede Plateau to the north and the Aire Mountains to the east, separated also by three depressions originated in the great fractures occurred millions of years ago..., the Mendiga depression..., the Mira de Aire "polje"..., and the Alvados depression. It is a typical protected area and has as its main characteristic the absence of defined and organized water ways, making it a paradox the importance of its extremely abundant presence underground which constitutes one the largest subterranean freshwater reservoirs in our country since it extends practically uninterrupted from Rio Maior to Leiria where the faults, cracks and tears in the rocks allow for the water's infiltration in the soil entering into a vast and complex network of subterranean waterways which form natural and vertical openings named "algares" which access a vast and gigantic subterranean world which is little known and explored.

At the Aire and Candeeiros Mountains Natural Park this millenary water circulation dissolved and deposited the limestone very slowly along millions of years thus creating a large diversity of speleogical themes which originate of the slow transformation into "stalactites" and "stalagmites" very characteristic of these underground spaces which we call caves, and the whole massif is now a vast territory looked from a different perspective for the resources it has, the richness it means, and the potential offered, allowing natural resources to have an extraordinary importance at the level of the landscape and the geological and biological diversity of the water resources available. The massif's individualization and the geological environment occured due to important tectonic flaws which have affected and still affect the region today, giving rise to huge faults which are manifest in the very steep slopes which characterise the existing landscape and turn it into a rough but unusual place whose natural beauty is the essence of the uniform and common landscape throughout the whole of the Aire and Candeeiros Mountains Natural Park.

Porto de M�s is a municipality which has had for thousands of years petrified dinosaurs and turtle remains which at present are in the municipal museum and all the pre-history of this region is founded on the axes and stone hewn tips of the Palaeolithic period, the polished stones of the Neolithic, the ceramics and coppers of the Chalcolithic period, the looms weights, the honey processing stones, the coins and the iron spears of the time of the Roman Empire. To walk the fabulous stone roman walk at Alqueid�o da Serra or the hills of limestone and windmills which surround the stone villages of the Candeeiros, Santo Ant�nio and Aires Mountains allow for the discovery from the Alto dos Moinhos Velhos a fruit growing scenery which stretches to the valley of the Lena River and the old town of Porto de M�s, embracing the dolomitic hillock of its castle, one of the most emblematic castles in Portugal. The entrance arch in the main body of the building is topped by a "loggia" with four countercurved arches, supported by chapitels and columns of manueline sculpting which lead onto the various rooms of gothic carvings fillets. It should also be underlined of touristic interest S. Pedro's Church in the baroque style and which rises at the top of the town and was formerly part of the Barefoot Augustinians Convent.

Porto de M�s is a municipality set in the limestone body of the quiet and majestic landscapes of the Aire and Candeeiros Mountains thus presenting a remarkable natural space where the valleys were accentuated due to glacier movement in eras more recent than those when the continental plates alterations of millions of years ago. While the river erosion was fracturing and opening cracks and openings of vertical progression named "algares" which allow sometimes difficult access to grottos, galleries, halls or underground wells which at certain points develop in vast natural caves, characteristic to the Aire and Candeeiros Mountains Natural Park where the municipality is set, which possesses a fantastic group of carsic aspects derived from the continental plates movements which started millions of years ago and which originated the countless caves decorated with "stalactite" and "stalagmite" spectacular formations which very slowly evolved at a rate of about a centimetre every thirty years and are the reason and the touristic attraction of the Alvados Caves and the Santo Ant�nio Caves, which belong to this millenary municipality whose historic and natural heritage charms visitors.

Alvados is a borough which represents the history of mankind in the "Alvados" lands and the oldest written reference to Alvados appears in the Leiria charter of 1142, but the borough was probably created between 1555 and 1559 and although existing for various centuries, it keeps many of the testimonials of its past..., such as the main church devoted to Our Lady of Consolation dated from the XVII were you can see and admire its beautiful altars of gold-leaf carvings. Located in the northern extremity of the Aire and Candeeiros Mountains Natural Park, at 300 metres altitude, its inhabitants dedicated themselves mainly to agriculture, producing olive oil and cereals, rock extraction, an activity which lasts until today, and the textile industry, today rather more forgotten, but it is tourism which now appears as a preferential activity. The Alvados borough is well positioned geographically along the imposing Alvados plateau and is 10 km away from Porto de M�s, 15 km from F�tima and 30 km from Leiria, making it thus one of the central accesses to the Aire Mountain where the famous Alvados Caves and Santo Ant�nio Caves are the main tourist attraction of the region.