Go into the collegiate church and find the Pórtico de la Majestad — reached from inside — with its original paint still on it

Work out how unusual that is — most medieval portals lost their polychrome long ago

Taste Tinta de Toro and work out why it is so much heavier than Ribera or Rioja

Find out why the vines here are ungrafted, and what phylloxera did not do to this sand

Work out what the battle of Toro in 1476 settled and what would have happened otherwise

The battle of Toro in 1476 effectively settled the Castilian succession in favour of Isabella, which makes this small town on the Duero one of the hinges of Spanish history. Its collegiate church has the Pórtico de la Majestad, a Gothic portal reached from inside the church and one of very few anywhere that still carries its original polychrome. The wine is Tinta de Toro, a Tempranillo variant that produces something considerably heavier than Ribera or Rioja, from old bush vines on sandy soil that phylloxera never took.

Toro: A Battle, a Wine and a Portico

Go to the treaty house and work out that two men in this town drew a line through an ocean neither had seen

Find out where the meridian actually fell, and why Brazil ended up on the Portuguese side of it

Go into the Real Monasterio de Santa Clara, a Mudéjar palace turned convent

Find out what happened to Joanna of Castile here, and for how long

Work out what the earlier Treaty of Alcáçovas of 1479 had already settled, and what Columbus's return upset

On 7 June 1494, in this small town on the Duero, representatives of Isabella and Ferdinand and of John II of Portugal agreed to divide the Atlantic and everything beyond it along a meridian, and excommunication was decreed for anyone crossing it without Castilian permission. That line is why Brazil speaks Portuguese. UNESCO added the treaty to its Memory of the World register in 2007 as a document shared between Spain and Portugal. Joanna of Castile — Juana la Loca — was later confined in the town for decades.

Tordesillas: Where They Divided the World

Go into the Castillo de la Mota and find out who was held in it — Pizarro's brother, Rodrigo Calderón, Cesare Borgia — and which of them got out

Work out what the ferias de Medina actually were and why a payment date here mattered in Antwerp

Find the house where Isabella the Catholic died in 1504, and find out what she was granted here in 1468 and lost in 1470

Walk the Plaza Mayor de la Hispanidad, which is where the fairs were held

Work out what happened to the town when the fairs moved, and what is left of the money

Medina del Campo held the great fairs of Castile, and they were not markets so much as clearing houses — bills of exchange settled here set the rhythm of European finance in the 15th and 16th centuries, and the phrase ferias de Medina meant a payment date across the continent. Isabella the Catholic died in the town in 1504. The Castillo de la Mota is built of the reddish local brick with stone only for gun ports and coats of arms. Isabella was granted Medina, its alcázar and the Mota tower under the 1468 accord of the Toros de Guisando, and lost it again in 1470 when her brother gave it to his daughter Juana. It later became a state prison holding Hernando Pizarro, Rodrigo Calderón, the duke of Calabria, the count of Aranda — and Cesare Borgia, who escaped from it. The town declined with the fairs and never regained the position.

Medina del Campo: Where Castile Did Its Banking

Count Romanesque churches — twenty-four of them from the 12th and 13th centuries, more than any other city in Europe

Look up at the cathedral cimborrio: sixteen windows in the drum and a dome clad in stone scales, built between 1151 and 1174

Work out what it started — the same dome copied at the Old Cathedral of Salamanca, at Toro and at Plasencia

Go into the cathedral museum for the Franco-Flemish tapestries, including four of the original eleven panels of a Trojan War series woven at Tournai around 1470

Come for Holy Week, which is the town's biggest event of the year by a distance

Zamora has twenty-four Romanesque churches of the 12th and 13th centuries in one small town on the Duero — more than any other city in Europe, which is why it gets called a museum of Romanesque art. The cathedral went up between 1151 and 1174, and its cimborrio is the thing to come for: a drum pierced by sixteen windows carrying a gallooned dome clad in overlapping stone scales, Byzantine in feel and unlike anything before it. It became the model for the Old Cathedral of Salamanca, the collegiate church at Toro and the chapter house at Plasencia.

Zamora: More Romanesque Churches Than Any City in Europe

Stand in front of the portal of the Colegio de San Gregorio, then walk round its patio

Find the work of Alonso Berruguete, the artist at the centre of the collection

See the Neapolitan nativity scene in the Palacio de Villena across the street

Visit the Casa de Cervantes, where he lived in 1605

The Museo Nacional de Escultura in Valladolid holds the most important collection of Spanish sculpture on the peninsula, from the late Middle Ages to the early 19th century, with Alonso Berruguete at the centre of it. Its main building, the Colegio de San Gregorio, was a Dominican college of theology and is one of the finest buildings of the Catholic Monarchs' reign, famous for its portal and its patio; next door stands the church of San Pablo, built between 1445 and 1616. The collection spreads across the street into the Palacio de Villena, which shows a Neapolitan nativity scene, and the Casa del Sol, home since 2012 of the national collection of casts. A few minutes' walk away is the house where Miguel de Cervantes lived in 1605 — or rather the one room of it his family had.

Valladolid: The National Sculpture Museum and Cervantes's House

Find the toad on the skull on the Escuelas Mayores facade — everyone calls it a frog, and students are told they will not graduate until they spot it unaided

Work out what the School of Salamanca argued in the 16th century about the morality and laws of colonisation in the Indies

Stand in the Plaza Mayor, built by the Churriguera family in two phases between 1729 and 1755 and originally used for bullfighting

Find both cathedrals, old and new, built against each other and both still standing

Find out why Fray Luis de León, released after four years in the Inquisition's cells, is said to have begun his next lecture here with 'as I was saying the other day'

Come back at sunset and see why the sandstone gives the place its nickname

The University of Salamanca was founded by Alfonso IX in 1218 — the oldest university in the Hispanic world and the fourth oldest anywhere still in continuous operation. Its mathematicians studied the calendar reform commissioned by Gregory XIII and proposed the solution that was eventually adopted, so the dates on your phone were worked out here. The city is built of local sandstone soft enough to carve like wood and gold in low sun, which is why its Plateresque facades are the most extravagant in Spain. The old city has been a UNESCO World Heritage Site since 1988.

Salamanca: The Golden City and Its University

Walk the wall and the Fortaleza above the Tormes gorge

Cross the bridge and work out which parts of it are Roman and which medieval

Walk into the dehesa around the town, which is fighting-bull country

Take the waters at Baños de Ledesma, which have been used since the Romans

Go on west into the Arribes, which starts a short way beyond the town

Ledesma stands above a gorge of the Tormes with a medieval wall, a bridge with Roman foundations, and the Fortaleza above it — a town that was a serious military position on the road between Salamanca and Zamora and then stopped being one. The countryside around is dehesa, some of the best fighting-bull country in Spain, and the town sits at the edge of the Arribes. Its Roman and medieval bridge is still the crossing, and the hot springs at nearby Baños de Ledesma have been used since Roman times.

Ledesma: A Walled Town on the Tormes

Find the Puerta del Perdón on the church of Santiago and work out exactly what it was for

Work out how far a pilgrim has walked to reach it and what is still ahead of them

Walk the Calle del Agua, the street of the old noble houses, down to the river

Go into the castle-palace of the marquises at the top of the town

Look west at the climb to O Cebreiro, which is what the door was there to excuse

The church of Santiago at Villafranca del Bierzo has a Puerta del Perdón, and it exists for a specific and humane reason: a pilgrim who had walked this far and was too ill to cross the mountains into Galicia could pass through this door and receive the same indulgence as if they had reached Compostela. It is one of very few such doors anywhere on the route. The town sits where the Burbia and Valcarce meet at the western edge of the Bierzo, with the Ancares behind it, and it has the look of a Galician town that has not quite arrived.

Villafranca del Bierzo: The Door of Forgiveness

Walk round the wide moat and work out that the brick is doing the decorating as well as the holding up

Find where limestone is used instead of brick — the arrow slits, the courtyard columns — and work out why

Climb the brick spiral inside the keep to the chapel and the armoury

Find the Roman wall of Cauca on the edge of the town

Find out which Roman emperor was probably born here

The castle at Coca was built in the 15th century and is reckoned one of the finest works of Spanish Gothic-Mudéjar architecture — principally brick, used as decoration as much as structure, with limestone kept for the arrow slits, the courtyard columns and a few details. A wide, deep moat runs all round it, the lower enclosure is square with four corner towers, and a narrow brick spiral inside the keep leads up to a chapel and an armoury. It belongs to the house of Alba and has been ceded to the state since 1954. Coca was also Roman Cauca, where the emperor Theodosius the Great was probably born, and stretches of its Roman wall survive on the edge of the town.