Walk the paved sections up towards the Fuenfría pass through the pine forest

Find the bridges — Enmedio, Descalzo, La Venta and Reajo — proposed for protection in 1981

Work out the argument: the visible track is not the 1st-century road along its whole length

Find out what the Cercedilla milestone of 1910 settled and what it did not

Cross the pass and look down into the Valsaín valley on the Segovia side

A Roman road crossed the Guadarrama here, linking Segovia with Miaccum and on to Toledo, over the Fuenfría pass between the Fuenfría and Valsaín valleys. A milestone turned up at Cercedilla in 1910 and let the archaeologist Antonio Blázquez date the crossing securely, though his reconstruction of the line has been argued over ever since — later work by Rivas López, Rodríguez Morales and Moreno Gallo showed the present paved track does not follow the 1st-century road everywhere. The road and its four bridges were put forward for protection on 2 July 1981.

The Fuenfría: A Roman Road Over the Guadarrama

Go into the basilica and work out that every metre of it is cut into the rock

Work out who built it: Republican political prisoners, between 1940 and 1958

Find out how many are buried here, from which sides, and why they cannot now be separated

Find out what was moved out in 2019 and in 2023, and what the 2022 renaming was for

Decide for yourself what a country should do with a monument like this, which is the live argument in Spain

Franco ordered this built in 1940 and it went up between 1940 and 1958, largely with the labour of Republican political prisoners. A basilica entirely underground, an abbey, and a cross 150 metres high on the crag above. Shortly before it opened in 1959 the remains of Republican soldiers were brought in, so 33,847 dead from both sides lie here, mixed together — the largest mass grave in Spain, and the bodies are now so far into the fabric that exhumation is considered impossible. Franco's own remains were moved out in 2019 and José Antonio Primo de Rivera's in 2023. It was officially renamed the Valle de Cuelgamuros in 2022.

Cuelgamuros: The Valley of the Fallen

Hike from the Puerto de Cotos to the summit of Peñalara at 2,428m, the highest peak of the Sierra de Guadarrama

Look down on the glacial lake and cirques beneath Peñalara, protected as the Peñalara Natural Park in 1990 and now part of the Sierra de Guadarrama National Park, declared on 26 June 2013

Visit the Peñalara visitor centre at the Puerto de Cotos, the start of the summit path

Peñalara is the highest point of the Sierra de Guadarrama at 2,428 metres, an hour from Madrid, and the corries beneath it hold the southernmost glacial lakes in Europe of their kind — cut by ice that has been gone for ten thousand years. It was protected as a natural park in 1990 and folded into the Sierra de Guadarrama National Park when that was declared on 26 June 2013. The path from Cotos is short and popular, which is why numbers to the summit are now limited at busy times.

Peñalara and the Glacial Cirques

Walk the upper gallery and work out that this is a palace wearing a castle's clothes

Find the Romanesque-Mudéjar church swallowed inside the structure when the castle was built over it

Work out Juan Guas's Isabelline Gothic and its Hispano-Muslim borrowings, and what he did next at Guadalajara

Find the remains of the old castle nearby, which this one replaced

Walk up into La Pedriza behind it, the granite massif the family's land ran into

The Mendoza were one of the most powerful families in late medieval Castile, and in the last third of the 15th century they replaced their old fortress at Manzanares with something grander — a palace-fortress built over a Romanesque-Mudéjar church, which was simply absorbed into the structure. Juan Guas drew it in Isabelline Gothic with Hispano-Muslim influence, and it is regarded as the precursor of his Palacio del Infantado at Guadalajara, where he settled the template for a Catholic Monarchs palace. It stands under the Guadarrama beside the Santillana reservoir, with La Pedriza behind it.

Manzanares el Real: A Castle Built to Be Lived In

Be there when the fountains run and work out that all twenty-one are driven by slope alone, with some jets clearing forty metres

Find El Mar, the 216,000 cubic metre reservoir at the top of the garden that feeds the whole system

Work out the contradiction: a Spanish king raised at Versailles who said he wanted another Escorial and built this instead

Find out why the palace is irregular — the 1719 order that nothing already standing was to come down — and why the fountain statues are lead rather than bronze

Go to the Real Fábrica de Cristales in the village, the royal glass works that supplied the palace

Philip V was born at Versailles in 1683 and raised at the court of his grandfather Louis XIV, and when he came to build himself a retreat below the Guadarrama it showed. He ordered a chapel here in 1719 with the instruction that nothing old was to be demolished, which is why the result is irregular and reads as a set of additions. The main works began in 1721. The gardens were laid out by the French gardener René Carlier, who used the natural slope of the surrounding hills both for the perspective and as the power source for all twenty-one monumental fountains; Carlier died in 1722 and Étienne Boutelou continued the work. Where Versailles struggled for water pressure, La Granja simply fell downhill — and some of its jets clear forty metres.

La Granja de San Ildefonso: Versailles on the Meseta

Tour the Royal Monastery of San Lorenzo de El Escorial, built between 1563 and 1584 for Philip II and a UNESCO World Heritage Site since 1984

Walk the Royal Library, which holds over 40,000 volumes

Visit the Royal Pantheon that holds the remains of Spanish monarchs and the Hall of Battles with its military victory frescoes

Philip II built El Escorial between 1563 and 1584 as a monastery, a palace, a library, a school and a royal burial vault all in one granite block in the Sierra de Guadarrama — and he ran an empire from a small bare cell in the middle of it with a window into the church, so he could hear mass from his bed. It is the most complete statement of what the Spanish Habsburgs thought they were doing that exists. The library holds over 40,000 volumes and the pantheon holds most of the kings of Spain since Charles V.

El Escorial: Philip II's Royal Monastery

Go into the church and find the grille made by the Carthusian monk Francisco de Salamanca

Find the walnut choir stalls carved in the 16th century, removed to Madrid in 1883 and returned here in 2003

Work out the founding story: a king who burned a charterhouse in France and built this one in 1390 to make up for it

Walk the Lozoya valley around it, which is inside the Sierra de Guadarrama National Park

Cross to the Puente del Perdón and find out what it was called that for

Henry II of Castile ordered a charterhouse built in the Lozoya valley in 1390 — the first Carthusian foundation in Castile — and tradition says he chose that order because his own army had burned one of their houses during the war in France. He picked the spot himself, beside a hermitage already there, and told his son, the future John I, exactly where. It was Carthusian until 1835. The grille separating the congregation from the monks was made by a Carthusian monk, Francisco de Salamanca, and the 16th-century walnut choir stalls were taken to Madrid in 1883 and only brought back in 2003.

El Paular: The First Carthusian House in Castile

Stand in the Plaza Mayor and work out that the stone under your feet came from the edge of the town

Go and look at the quarries, which supplied a great deal of Madrid as well as this square

Find out what a tinaja is and why making them was an industry here

Go to the Ulpiano Checa museum and find out who he was

Work out the reversal: the second town of the province in the 19th century, and what it is now

Colmenar de Oreja was, until well into the 19th century, the second most populous town in the province of Madrid after the capital itself — built on stone quarrying, the making of tinajas, wax, esparto, textiles and farming. Its Plaza Mayor is a large arcaded square of local stone, and the quarries that supplied it and much of Madrid are on the edge of the town. The painter Ulpiano Checa was born here and has a museum. Nine wineries work under the Vinos de Madrid designation, in the Arganda subzone.

Colmenar de Oreja: A Town Built of Its Own Quarry

Walk along the top of the channel and work out that nothing in the structure is mortared

Work out the fall — forty centimetres over 217 metres, which is what kept the water moving

Stand underneath and look up 27 metres at two tiers of arches

Work out where the water was coming from: twenty-five kilometres away, along the Francolí

Find out why it is locally called the Devil's Bridge, which is a common name for Roman work nobody could explain

Four kilometres north of Tarragona, in pine woods off the old road, a Roman aqueduct arcade stands almost intact: 217 metres long, 27 metres at its highest, two tiers of arches in dry-jointed ashlar with no mortar anywhere in it, and a fall of forty centimetres from the north end to the south to keep the water moving. It carried water twenty-five kilometres into Tarraco along the Francolí. Locally it is the Pont del Diable, the Devil's Bridge, because a Roman structure that good in the middle of a wood needed explaining.