The journey starts in the old lands of León, in the Sanabria district of Zamora. Puebla de Sanabria, a listed historic town, watches over the natural pass between the Meseta and Galicia from the castle of the Counts of Benavente.

Crossing the Sierra de la Culebra and the Serra de Montesinho, you enter Trás-os-Montes, one of the most mountainous and isolated parts of Portugal. That isolation has preserved ancient traditions such as the masked caretos rituals.

• Bragança · former seat of the country's most powerful dukedom. Its walled medieval citadel holds the Torre de Menagem keep and the Domus Municipalis, an extremely rare Romanesque civic building.

Heading south, the land flattens into the Planalto Mirandês until the Douro breaks through it, carving canyons up to 400 metres deep. This natural border forms the Arribes del Duero Natural Park in Spain and the Douro Internacional Natural Park in Portugal.

• Miranda do Douro · heart of Mirandese culture, where people still speak Mirandese, an officially protected Astur-Leonese language.
• Fermoselle · back in Zamora, a medieval village whose ground is honeycombed with hundreds of wine cellars dug by hand into the bedrock.

Leaving the Douro behind, you enter Riba-Côa, a granite plateau shaped by the river Côa. The kingdoms of León and Portugal fought fiercely over this land until the Treaty of Alcañices. To secure the border, Portuguese kings built a dense network of fortified villages, today known as the Historical Villages of Portugal.

• Pinhel · the "falcon city", ringed by hills and guarded by two towers.
• Almeida · a gem of military architecture: its walls form a twelve-pointed star, with 17th-century bastions designed to withstand heavy artillery.
• Castelo Mendo · a village that keeps its medieval walls, guarded by ancient stone boars (berrões).
• Sabugal · an unusual castle with a pentagonal keep.
• Sortelha · one of the most beautiful villages in Portugal, wedged between granite masses and crowned by a fortress on the rocks.

Crossing into the Tagus basin, the landscape changes: the plains of Beira Baixa give way to small ranges and hills of olive and holm oak.

• Monsanto · houses merge with giant granite boulders that serve as walls, roofs or foundations, below the ruins of a Templar castle.
• Alcántara · back in Cáceres, the Tagus and its Roman bridge, a 2nd-century masterpiece that has survived battles and floods for almost two thousand years.
• Valencia de Alcántara · in the São Mamede natural park, home to one of the most important groups of megalithic dolmens in Europe.
• Marvão · right across the border, a medieval eagle's nest at almost 900 metres on a sheer crag.
• Castelo de Vide · whitewashed façades and one of the best-preserved medieval Jewish quarters in the Iberian Peninsula.

From here the relief softens and the Alentejo and the province of Badajoz open up: the land of cork and holm-oak pastures. These plains were the stage for the battles of the Portuguese Restoration War (1640–1668).

• Elvas · the largest bastioned fortification in the world, a UNESCO World Heritage Site for its star forts and the Amoreira aqueduct.
• Olivenza · Portuguese until 1801. Its Manueline architecture, cobbled streets and the dual nationality of many residents show the most welcoming face of the Raya.
• Serpa · still keeps much of its walled enclosure.
• Mértola · above the Guadiana, a key river port since Phoenician and Roman times. It keeps the only church in Portugal that was once a mosque (12th century), with its mihrab still facing Mecca.

The route follows the banks of the Guadiana down to the Atlantic Ocean in the eastern Algarve. On the way you cross the river on the small ferry between Sanlúcar de Guadiana and Alcoutim.

• Vila Real de Santo António · a border port town built in record time in 1774 by the Marquis of Pombal. Its perfect grid and the Praça Marquês de Pombal follow Enlightenment ideals after the Lisbon earthquake. The perfect place to celebrate the end of the journey.