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.

The Ferreres Aqueduct in the Woods

Sit in the amphitheatre, built around the turn of the 1st and 2nd centuries AD below the walls and facing straight out to sea

Find the remains of the Roman circus where the chariot races were run — the medieval town grew over and around them, so they sit inside the old quarter now

Walk the archaeological promenade along the top of the Roman walls

Go out to the Pont del Diable, the Ferreres aqueduct — 217 metres long, 27 metres high, two tiers of arches in dry-jointed ashlar, part of a system that brought water 25 kilometres

Find out about castells, the human towers that started at Valls just up the road as the Ball dels Valencians, first documented in 1712 and on the UNESCO intangible heritage list since 2010

The Romans developed Tarraco during the Second Punic War and it became the gateway through which they took and held the Iberian peninsula — first Colonia Iulia Urbs Triumphalis Tarraco, capital of Hispania Citerior, then capital of the province named after it, Hispania Tarraconensis. It stands on a rock 75 to 90 metres above the sea, which earned it the epithet arce potens Tarraco, Tarraco the mighty citadel. The archaeological ensemble went onto the UNESCO World Heritage list in 2000.

Tarragona: Tarraco, Gateway to Roman Spain

Walk the Gothic cloister and work out how much carving a Cistercian house was supposed to permit

Find out who Reinard de Fonoll was, what an English mason was doing in 14th-century Catalonia, and what was demolished to let him build

Find the royal pantheon built for Peter III the Great, and the tombs of James II and Blanche of Anjou

Find the abbot's rooms James II turned into a royal palace, and the walls Peter IV threw round the lot

Do the Ruta del Císter properly and add Poblet and Vallbona de les Monges

Santes Creus is the second of the three great Cistercian houses of the Catalan Ruta del Císter, with Poblet and Vallbona, and the one with the finest Gothic cloister — built by the English master Reinard de Fonoll with Guillem de Seguer after James II had the Romanesque cloister pulled down to make room for it. Peter III the Great asked to be buried here and the royal pantheon was built for him in the 13th century; his son James II and James's queen Blanche of Anjou lie here too. James also turned the abbot's rooms into a royal palace, and Peter IV walled the whole place. The monastery is unusual in having a village living inside its walls, in the buildings the community left behind.

Santes Creus: The Other Cistercian Pantheon

Find what is left of the castle, the last Muslim stronghold in Catalonia

Go into the Romanesque church of Santa Maria de Siurana

Look down from the cliff to the Siurana reservoir far below

Siurana is a hamlet of a few dozen people at about 740 metres on the edge of a limestone cliff at the end of the Prades mountains, above the Siurana river. Its castle, on a rise in front of the village, guards the only natural way in, and the Christian walls are built over a Muslim fortress: Siurana was the last Muslim stronghold in Catalonia, taken by Ramon Berenguer IV's forces in 1153–1154 after a siege, some years after Tortosa and Lleida had fallen. The Romanesque church of Santa Maria stands in the village, and the Siurana reservoir lies far below, at about 470 metres.

Siurana: The Last Muslim Stronghold in Catalonia

Stand under the royal tombs raised on arches across the transept — the pantheon of the Crown of Aragon

Walk the cloister and work out what the Cistercians were actually after: water, isolation and farmland

Find the monks' dormitory, which is one of the largest surviving Cistercian dormitories anywhere

Work out the founding: given to monks from Fontfroide in 1149, community established 1153

Remember that this is a working monastery again, and that some of what you cannot see is why

Ramon Berenguer IV gave this site to Cistercian monks from Fontfroide in 1149 and the community was established under its first abbot in 1153 — it met everything the order asked for in a foundation: isolation, plenty of water and land to farm. It became the royal pantheon of the Crown of Aragon from the end of the 14th century until the royal house died out, and it is the prototype of the Spanish Cistercian abbey. UNESCO listed it in 1991. Cistercians live in it again, so parts of it are enclosure and closed to visitors.

Poblet: The Royal Pantheon of the Crown of Aragon

Visit the ruins of Scala Dei Charterhouse, founded in 1194, whose Carthusian monks introduced viticulture to the region and gave Priorat its name from the prior's authority over seven villages

Taste a Priorat DOQ wine in Gratallops, where René Barbier and Álvaro Palacios led the region's revival in the 1980s

Walk the terraced vineyards on llicorella, the black and red slate soil laced with mica that forces the Garnacha and Cariñena vines deep

Carthusian monks founded Scala Dei in 1194 and planted vines, and the priory's authority over seven villages gave the region its name — Priorat. The soil is llicorella, black and red slate shot through with mica, which holds almost no water and forces old Garnacha and Cariñena vines to send roots metres down to find it. The result is concentrated and expensive. The region had all but died by the 1970s; René Barbier, Álvaro Palacios and a handful of others revived it in the 1980s, and it is now one of only two DOQ regions in Spain.

Priorat: Scala Dei and the Llicorella Vineyards

Go into the Cau Ferrat and work out that the wrought iron collection is the reason the house is called that

Find the two El Grecos Rusiñol paraded through the streets when he brought them here

Work out what the Festes Modernistes from 1892 were for and what came out of them

Go next door into the Maricel and out along the seafront the pair of them face

Come for Carnival in February, which is one of the biggest in Catalonia

Santiago Rusiñol bought two fishermen's cottages on the seafront at Sitges, knocked them together and made the Cau Ferrat — part studio, part museum of the wrought iron he collected, and the venue for the Festes Modernistes from 1892, where Catalan Modernisme was effectively launched as a movement. Two El Greco paintings hang in it, which he carried through the streets in procession. Next door is the Maricel, and the town behind is a compact white grid on a headland. Sitges also has one of the largest carnivals in Catalonia and is a long-established gay resort.

Sitges: The Town Modernisme Was Argued Out In

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

Cross the medieval bridge and find the gate tower built into the middle of it

Work out what the tower was for and what the town charged for

Come on Good Friday for the Vía Crucis Viviente, performed through the streets by several hundred locals

Work out what it means that this was the first chartered town in Biscay, in 1199

Walk the old quarter and the riverside, which is what the road and the bridge built

Lope Sánchez de Mena chartered Balmaseda in 1199, making it the first town in what is now Biscay to receive a fuero, and it grew on the natural pass between the Castilian meseta and the Cantabrian coast — which is what the medieval toll bridge over the Cadagua with a gate tower in the middle of it was for. Its Good Friday Passion play is one of the oldest and largest in Spain, with several hundred townspeople taking the parts, performed through the streets of the old quarter rather than on a stage, and it draws thousands.