Many navigation routes made port along the coast so there is evidence of the settlement of a Celtic tribe, the Ártabros. The most documented history belongs to the Castreña (Hill Fort) culture, which is manifested at present by castros (fortified villages) that are preserved to different degrees. They correspond to the typology of the Castreña civilization in Galicia. They are situated in high places where a settlement of round huts surrounded by a defensive wall with ramparts and terraces is located. The castro de Punta Roza, which can be seen on this route, is of particular note.
This route can be followed by starting and ending at two different points; either from the Porto de Dexo or from the church of Santa María de Dexo. It is a Romanesque church from the twelfth century. According to the tradition a monk, who was a distant descendant of Cayo Serbio Lupus, built it to settle there when fleeing from the possible discovery of the sins that would cause him to lose his religious occupation. In 1108 it was consecrated by the archbishop of Santiago and in 1903 suffered a fire which it survived with the construction still in good condition.
It has a single quadrangular nave finished with a semicircular apse. The main façade follows the typical Romanesque structure three doors open to the exterior: two lateral doors with round arches and the main door which is more interesting. It consists of three semicircular archivolts with geometric decoration and in the tympanum there is a cross. It is crowned with a double bell-gable from a later date. The exterior wall on which the eaves rest has representations of human and animal heads, the image of a lamb, the Mystic Lamb, being particularly important.
Along the route we come to the mill of Dexo. In the municipality of Oleiros there are a great number of watermills located on the banks of rivers. These rural constructions proliferated at the same time that maize was introduced in the region. They are buildings made with flagstones next to small waterfalls, which have grown old with the passage of time and have merged into the natural environment.
The settlement of this village is due to the natural resources provided by the sea and the strategic location of the natural harbour of Dexo. Restricted to a cove of small dimensions, it determined the method of fishing and navigating as they could only use small boats and specific devices to load and unload the perishable goods, such as the guindastre. The evolution in fishing systems and the difficulties of access to the harbour promoted the fact that at present it could be only enjoyed as a beach. From this point and some others along the route we can see the islet called A Marola, which inspired the seafaring saying “Quien pasa A Marola pasa la mar toda” (Those who pass A Marola pass the whole sea) because of the force and the roughness with which it is beaten by the sea.