Be at Valencia Cathedral's Door of the Apostles on a Thursday at noon to see the Water Tribunal, the customary court of the Huerta's irrigation canals, thought to date from around 960 and inscribed by UNESCO as intangible heritage in 2009

Drink horchata de chufa, the tiger-nut drink, with fartons in Alboraya, the main production centre, which yields about 8,000 tonnes of chufa a year

Cycle beside the Huerta's irrigation canals (acequias) north of the city

Every Thursday, in public at the Door of the Apostles of Valencia Cathedral, elected farmers settle disputes about irrigation water. The court is purely oral — nothing is written down and no records are kept — and the whole thing is over in minutes. It is described as the oldest court in the world and the oldest democratic institution in Europe, and UNESCO inscribed it in 2009 alongside the Council of Wise Men of the Murcia plain.

Valencia's Huerta: Water Tribunal and Horchata

Stand in the trading hall of the Llotja among its eight twisted columns, eleven metres high — meant as palm trunks holding up a sky once painted blue with gold stars

Look for the carved gargoyles on the outside of the Llotja

Shop in the Mercado Central, the modernista market finished in 1928

See the Holy Chalice in its chapel in Valencia Cathedral, given by Alfonso the Magnanimous in 1437

The Silk Exchange in Valencia, the Llotja, was designed by Francesc Baldomar around 1470 and finished after his death by Pere Compte and Joan Ivarra, on the model of the exchange in Palma: a great hall of twisted columns holding up Gothic vaults, built to house the maritime trade court and to show off the city's 15th-century wealth. It has been a UNESCO World Heritage Site since 1996. Across the square the Mercado Central, begun in 1914 and finished in January 1928, is one of the masterpieces of Valencian modernisme and still a working food market. A few streets away, in a side chapel of the cathedral that was once its chapter house, is the Holy Chalice, dated to the 1st century and given to the cathedral by King Alfonso the Magnanimous in 1437.

Valencia: The Silk Exchange, the Central Market and the Holy Chalice

Cycle or run the old riverbed end to end, and work out where the water used to be relative to the city

Work out what almost happened instead: the 1960s plan was an urban motorway straight down the old channel

Ride under the historic bridges and notice that they now cross a park

Get to the Ciutat de les Arts i les Ciències at the seaward end and see what Calatrava and Candela built in a dry river

Find the Gulliver playground, which is a giant tied-down figure you climb over

On 14 October 1957 the Turia flooded Valencia and killed around a hundred people. The river was diverted south of the city — the works finished in 1972 — leaving kilometres of empty riverbed through the middle of town. The plan of the 1960s was to run an urban motorway down it; the new ring road made that idea redundant and the city got a park instead, founded in 1986, and the old channel is now a continuous green corridor with pitches, running tracks, cycle paths and gardens, passing under the historic bridges that no longer cross anything. At the seaward end Santiago Calatrava and Félix Candela built the Ciutat de les Arts i les Ciències in the dry bed.

Valencia's Turia: A Riverbed Turned Into a Park

Take a traditional boat trip on the Albufera lagoon, the freshwater lake 11km south of Valencia in a 21,120-hectare natural park

Look for waterbirds — more than 250 species have been recorded at the Albufera

Walk the dunes and pinewoods of the Devesa del Saler, the coastal strip separating the lagoon from the sea

Visit a barraca, the traditional thatched house of the Albufera

The Albufera is a freshwater lagoon eleven kilometres south of Valencia, separated from the sea by a wooded dune bar and surrounded by rice fields — 21,120 hectares of natural park, with over 250 bird species recorded. It was a royal hunting preserve for centuries, which is why it survived. Flat-bottomed boats still work it, the barracas with their steep thatched roofs are the traditional houses of the people who fished and farmed it, and the sunset over the lagoon from El Palmar is genuinely worth arranging a day around.

The Albufera: Boats on the Lagoon and the Barracas

Walk the castle ridge, which runs the length of the hill and covers every period from Iberian to Napoleonic

Sit in the Roman theatre cut into the hillside below the castle

Work out what Hannibal actually wanted here: money, men and a fortress for his brother

Find the Jewish quarter on the slope below the castle, one of the best preserved in Valencia

Work out how an eight-month siege of one town started a war that reached Italy

Sagunto was the Iberian oppidum of Arse, trading across the Mediterranean from the 6th century BC, and it became Roman Saguntum. In 219 BC Hannibal besieged it, and the townspeople's whole strategy was that their walls would hold long enough for help to come. It took him eight months. He wanted the place intact — to fund the march on Rome with its plunder, to conscript its fit men, and to leave his brother Hasdrubal a stronghold near Qart Hadasht, modern Cartagena — and that is exactly what he got. The siege is the trigger for the Second Punic War.

Sagunto: Eight Months Against Hannibal

Get a ticket — since 2013 attendance has been capped at 22,000 and you cannot simply turn up

Watch the palo jabón, because the battle does not start until somebody gets the ham down

Be in the Plaza del Pueblo when the lorry beds tip and the whole load goes into the street

Work out the numbers: about 150 tonnes of tomatoes, six lorries, one hour

Stay for the hosing down afterwards and work out how the town is clean again by the afternoon

On the last Wednesday of August, during Buñol's patronal week, six lorries move slowly through the Calle San Luis, the Calle Cid and the Plaza del Pueblo distributing close to 150 tonnes of tomatoes, and 22,000 people — the cap since 2013 — throw them at each other for an hour. It starts when somebody manages to get the ham off the greased pole and the rocket goes up, usually around noon. The best moment is when the lorry beds tip and the whole load goes into the street. Then the fire brigade hoses everything down and the town is clean by mid-afternoon.

La Tomatina: A Hundred and Fifty Tonnes of Tomatoes

Find the portrait of Philip V in the Museu de l'Almodí and check which way up it is hanging

Work out why: the town was burned in 1707 and renamed after the man in the picture

Walk the length of the castle along the ridge — it is two castles, the Castell Menor and the Castell Major

Find out which popes came from here, and what the Borja family did next

Find the Gothic Sant Feliu church below the castle, one of the oldest buildings left after the fire

Xàtiva backed the Austrian side in the War of the Spanish Succession, and in 1707 Bourbon troops burned the town in reprisal. Philip V then renamed it San Felipe, after himself; the Cortes of Cádiz gave the old name back in 1811. The town has not forgotten. In its museum hangs a portrait of Philip V, and it hangs upside down. Xàtiva was also the cradle of the Borja popes — Calixtus III and Alexander VI — and the twin castle on the ridge above, praised by al-Idrisi in the 12th century for its beauty and strength, runs along the whole crest.

Xàtiva: The Town Hung Upside Down

Visit the Parc Astronòmic Montsec near Àger and observe through the observatory telescopes — the facility operates public observation sessions under some of the darkest certified Class 1 skies in Catalonia

Walk the Congost de Mont-rebei gorge — the Noguera Ribagorçana river cuts a 500m canyon through the Montsec range, accessible only on foot along a clifftop path with sections of fixed iron ladder

Look for griffon vultures nesting in the Montsec cliff faces — colonies of 80+ pairs nest in the gorge and ride thermals above the observatory plateau throughout the day

Visit Sant Miquel d'Àger collegiate church and photograph the Romanesque apse against the dark pre-Pyrenean sky at dusk

A Class 1 IDA Starlight Reserve — the highest designation — in the Catalan pre-Pyrenees, where a world-class dark sky observatory sits above a gorge accessible only on foot and griffon vultures nest in the canyon walls below

Montsec: A Starlight Reserve Above the Mont-rebei Gorge

Climb Mont Caro, at 1,441m the highest point of the province of Tarragona

Look for the Spanish ibex, which lives in the Ports massif

From the top, pick out the Ebro delta and the Mediterranean below

The Ports de Tortosa-Beseit is a limestone massif where Catalonia, Aragon and Valencia meet, rising to Mont Caro at 1,441 metres with the Ebro delta and the Mediterranean laid out below it. It holds one of the strongest populations of Spanish ibex in the country.