Walk into the lower church and work out that the roof over your head is the mountain

Find the royal pantheon where kings of Aragon and Navarre were buried for five centuries

Go into the cloister under the overhang and look at the carved capitals

Find out what the founding legend of Aragon says happened here with Voto, Félix and Garci Ximénez

Find out what the monastery claimed to have kept, and where that object is said to be now

The old monastery of San Juan de la Peña is built directly under a vast rock overhang, with the cliff as its roof — the most important monastery in Aragon in the early Middle Ages, and the royal pantheon where kings of Aragon and Navarre were buried across five centuries. It reached its height under Sancho Ramírez. The founding legend of the kingdom of Aragon is set here: Christian fighters gathering with the hermits Voto and Félix and acclaiming Garci Ximénez as their leader. The Holy Grail was said to have been kept here before it went to Valencia.

San Juan de la Peña: A Monastery Under an Overhang

Walk the star-shaped ramparts of the Citadel of Jaca (Castle of San Pedro) — designed for Philip II in 1592 and never involved in a battle

Find the moat and drawbridge of the pentagonal fort, still the only way in

Inside Jaca Cathedral, find the carved capitals of the 11th-century Romanesque nave

Walk the arcaded main street connecting the cathedral to the citadel

Two buildings five minutes apart. The cathedral of San Pedro was begun in the last quarter of the 11th century on the initiative of Sancho Ramírez, at almost the same moment as Santiago de Compostela, and it carries the architectural vocabulary that then travelled the whole Camino — the chequerboard billet moulding and the ball ornament on the interior supports. The citadel is a five-pointed star fort on the Italian model, built outside the town walls and preserved essentially intact: ditch, bastions, scarps and counterscarps, barracks, powder stores and tunnels, entered across a three-arched bridge and a drawbridge. The Spanish army held it into modern times.

Jaca: Citadel and Cathedral

Stand at the foot of the Pisón and look up 275 metres of overhanging conglomerate

Work out what the rock actually is: river cobbles and gravel cemented in the Miocene and stood on end by the Pyrenees

Find the Visera and work out where sixty metres of overhang puts the top relative to the bottom

Learn the names of the towers — el Puro, el Cuchillo, la Visera, el Tornillo — and where each name came from

Watch the griffon vultures at the Paredón de los Buitres, which is named for them

Climb here if you climb — and if you do not, walk the path round the base, which gets you underneath all of it

The Mallos are towers of Miocene conglomerate — cemented river cobbles and gravel — thrown up when the Pyrenees rose, and they reach 275 metres at the north spur of the Pisón. The walls are vertical or overhanging, which is why they are one of the great climbing grounds of Spain; the Visera is reckoned the biggest overhang in the country, sixty metres out from the base of the tower to the vertical of the top. Each mallo has its own name, some from houses in the village, some from their shape. They were made a natural monument in November 2016.

Mallos de Riglos: Vertical Conglomerate

Climb the stair inside the walls and work out that the castle and the church are one building, not two

Go into the crypt of Santa Quiteria at the entrance and listen to what it does to sound

Find the dome over the castle church, which Romanesque builders rarely attempted

Work out the sequence: fortress, then enlarged by Sancho Ramírez around 1071, then a house of canons under papal protection from 17 October 1071

Stand on the wall and look out over the Huesca plain — the reason it was built exactly here

Loarre was built in the 11th century on a rock spur above the Huesca plain and is considered the best-preserved Romanesque fortress in Europe — one of the finest surviving examples anywhere of Romanesque military and civil architecture together. Sancho Ramírez enlarged it around 1071 and founded a house of canons in it, and on 17 October that year Pope Alexander II took it under his protection. Peter I later moved the congregation to Montearagón and Loarre stopped being a monastery. It has a church with a dome, which is unusual in Romanesque, and a crypt with extraordinary acoustics.

Loarre: The Best-Preserved Romanesque Castle in Europe

Walk the full 240m length of the station building and count some of its 365 windows

Find the section preserved as a small museum, documenting the station's role smuggling Nazi gold and hiding refugees between 1942–1944

Look for the plaque honouring Albert Le Lay, the French border guard called "the Schindler of Canfranc" for helping refugees escape

Walk a stretch of the disused rail line heading toward the sealed French border tunnel — the international route has been closed since 1970

Canfranc International station is 241 metres long with seventy-five doors on each side, built to the design of the engineer Fernando Ramírez de Dampierre and modelled on 19th-century French palace architecture. It took five years and was inaugurated on 18 July 1928. International services stopped between 1945 and 1949 over a falling-out with the French government, and then ended altogether on 27 March 1970 when a French freight train derailed and brought down the L'Estanguet bridge on the far side of the border. A new passenger station opened on 15 April 2021 in two rehabilitated freight sheds, and in 2023 a luxury hotel opened inside the old building itself.

Canfranc: The Belle Époque Station on the Border

Go to the costume museum in Ansó church and work out how many pieces the traditional dress has

Come on the last Sunday in August, when the village wears it

Find out what cheso is and how a dialect survives in one valley and not the next

Look at the chimneys on the houses and work out what they were built that size for

Drive up into the Selva de Oza and walk to the Boca del Infierno gorge

Ansó and Hecho are the two westernmost valleys of the Aragonese Pyrenees, and they kept a distinct identity long after the rest — their own dialect, Aragonese in a form called cheso in Hecho, and a traditional women's costume of such complexity that it is one of the most elaborate surviving folk dresses in Europe, still brought out for the last Sunday in August. The villages are stone and slate with enormous chimneys. Behind them the Selva de Oza and the Valles Occidentales park run up to the French border.

Ansó and the Western Valleys

Drive the full 40 km of the Aspe valley from Escot up to the col, and ignore the signs for the 8.6 km tunnel that has taken the traffic off this road since it opened on 7 February 2003 — the old pass road is the quiet one now

Stand on the frontier at the col by the Ermita del Pilar, the one building up here, and work out what the pilgrims coming up the Via Tolosane from Oloron-Sainte-Marie were facing: 840 km still to Santiago, down into Aragon on the Camino aragonés

Walk a stretch of the waymarked pilgrims' way down from the col towards Urdos, and find the abandoned works of the Pau to Canfranc railway in the valley beside it — opened in 1928 and shut after a goods train brought down the Estanguet bridge on 27 March 1970

Walk Borce for its medieval houses and the ecomuseum room on the pilgrim road, then cross to Etsaut and look up at the Fort du Portalet clamped to the gorge wall — known as the fort d'Urdos although almost all of it stands in Etsaut

Walk the Chemin de la Mâture above Etsaut, the ledge cut straight into the rock in 1772 so that trees from the bois du Pacq could be brought down to be made into ships' masts, and work out how a mast was got along it

The Somport sits at about 1,632m on the Spanish border where the Aspe valley opens into Aragon, and the Roman road up to it, the Via Tolosane, was the most popular of all the crossings for pilgrims heading to Compostela until the 12th century, when Roncesvalles became the safer choice. The Vandals, Alans, Suebi and Visigoths all came the other way through it in the early fifth century. The Aspe below is still wild country, and for a long time it was the refuge of the Pyrenean brown bear.

The Col du Somport: The Pilgrims' Pass Above the Aspe Valley

Go into the Palacio de Sada and find the room where Ferdinand the Catholic was born in 1452

Work out how the town got the second half of its name and when

Go into San Esteban and down into the crypt, which is the best thing in the town

Walk the walls and the Plaza de la Villa, protected as an ensemble since 1968

Work out what the Cinco Villas are and why Sos became their capital in 1711

Ramiro I took Sos into the kingdom of Aragon in 1044. In 1452, in the middle of the Navarrese civil war, Queen Juana Enríquez came to the town — then simply Sos — and gave birth to the infante Ferdinand, later Ferdinand the Catholic, in the Palacio de Sada. That birth added del Rey Católico to the name. It became capital of the Cinco Villas in 1711, and the whole historic centre was protected in 1968: walls, churches, the Plaza de la Villa and a church with a crypt and a cloister that opens off the street climbing from it.

Sos del Rey Católico: Where Ferdinand Was Born

Find the Torre de los Moreno of 1915 and work out what an indiano was

Walk the Eo estuary, which with the Oscos hills behind it is a UNESCO Biosphere Reserve

Cross the Eo bridge and work out that the far side is Asturias

Go up to Santa Cruz above the town for the view over the estuary and the coast

Work out what emigration to Latin America did to towns along this coast, and what it built when it came back

Ribadeo sits at the mouth of the Eo, which is the border with Asturias, and the Eo estuary with the Oscos hills behind it is a UNESCO Biosphere Reserve. The town made money from emigration to Latin America and came back in the form of indianos — returning emigrants who built showy houses, of which the Torre de los Moreno of 1915 is the extravagant example. The Eo bridge is a kilometre and a half of motorway over the estuary. Praia das Catedrais is ten kilometres west.