North of Porto lie the villages and farms of Portugal's Minho region, a place of wooded hills and river valleys stretching from the high mountains which form the border with Spain to the Atlantic coast. Whatever about the progress of recent years - and blue billboards acknowledging the aid of EU structural funds are a familiar sight - the Minho remains one of the more traditional parts of Portugal. On our first night there, not knowing the language, I point at the menu and order a local dish, Cozida a Minho. The plate arrives, filled with bacon, butter beans and stewed cabbage, and a dainty little pig's ear floating on top. For the rest of the holiday I keep a wary eye out for crubeens.
From Porto a slow train takes us through hilly country to Guimaraes, the capital of the first kingdom of "Portucale". The old town is gathered round the medieval Rua de Santa Maria, a cobblestone street with tall, balconied town houses and public buildings winding down the steep hill from the castle to Largo da Oliveira, the oldest of Guimaraes's many squares.
Though more and more people now live in the urban blocks which surround Portuguese towns, the square is the centre of social life, alive with people chatting under the market arches, sitting at cafe tables sipping fresh vinho verde, or simply leaning over the balcony railings to watch what's happening below.
At a pharmacy where a sign on the window lists the chemist shops which are on duty this Sunday, a local man reads our situation quicker than we can decipher the notice, taps us on the shoulder and points to a chemist open down the street. The Portuguese are immensely helpful, warm and polite, though their habit of spitting in public can be disconcerting and in the countryside litter often surpasses Irish proportions. No place would be complete without its contradictions: the tobacconist stocks FC Porto brand cigarettes and the off-licence Benfica whiskey. The heart of Guimaraes is a web of narrow streets and laneways, doorways opening into one-room shops - barbers' shops, drapers, grocers and craftsmen - and a sprinkling of places specialising in religious wares. As people go about their business, occasionally one stops at the shrines set in alcoves on the side of the street, says a quick prayer, and carries on with the day.
Portugal is a Catholic country. Beyond Guimaraes is Braga, an ancient town and the country's religious capital. At midday it is bleached by the sun, but the evening light picks out buildings embellished with blue and purple tiles and throws shadows into the streets around the old cathedral, the Se.
Founded in the 11th century, the Se embraces Gothic, Renaissance and Baroque styles; its treasury is one of the richest Catholic reliquaries in Europe. Tableaux of saints and crucifixion scenes stretch from floor to ceiling behind the altars of most churches in the Minho, but the sanctuary of the Se is a baroque monument to gilt and gold-leafing. Pilgrims flock here for Holy Week celebrations whose torchlit processions are led by hooded penitents. At Whitsun there is a pilgrimage to Bom Jesus in the woods outside the city, where a massive granite stairway climbs the hill, each landing a step in the life of Christ. The more devoted pilgrims climb the stairs on their knees. More often, people come out from the city at the weekend to picnic in the woods. Picnicking is immensely popular, and large family groups gather on river-banks or beauty spots on Sundays, spread tablecloths on the grass, pile them with food, and sit back in wonder at the tourists setting off on hikes in the scorching heat.
Come evening, locals and tourists alike gather at the restaurant tables set on the sidewalks or in town squares. Food is usually simple - the cuisine centres round meat and fish, with fish taking the larger part of the menu in restaurants as well as households. Waiters clatter between the tables in the high ceilinged, fin de siecle coffee houses of Braga, blica, delivering coffee, sweet patisseries and port. It is raining when we reach the coast, the Costa Verde - the woman in the tourist office in Viana do Castello tells us that this is "an accident". Portugal is a seafaring nation and in Viana, a city about the size of Limerick, the docks are busy with cargo ships and trawlers, while traditional timber-framed boats are built in small yards beside the river.
The town's elegant buildings and Renaissance squares are a solid reminder of the wealth Portugal enjoyed from the 16th to the 19th centuries: Viana itself produced some of the great colonists of the "Discoveries". The furniture shops here display the most exquisite cabinet-making skills, honed on the timber of Africa and Brazil.
There is an echo of Portugal's colonial world on the television news, which opens typically with the major events at home, takes a look across the border to Spain, and then turns its attention to Africa and the Far East. The English-speaking world lies somewhere in the distance.
Spain is just a few miles up the road, but we head along the Rio Lima which reaches the Atlantic at Viana. The Romans thought of the river as Lethe, the mystical River of Oblivion, beyond which lay the Elysian Fields. Their legions are said to have first crossed the river at the village of Ponte de Lima.
Wide sandbanks stretch out beneath the bridge, making perfect beaches for dipping in and out of the water on a hot summer's day. Locals use the banks more productively, to hang out lines of washing and hold a fortnightly market, and farmers arrive occasionally to shovel away a trailer-load of sand. A few miles further on is Ponte da Barca, and further on again more small villages and farms. In the Che Guevara bar in Ponte de Lima - the owner talks proudly of the day Che's brother paid a visit - some young lads complain about the quietness of the countryside and say they have to go across to Spain even to find a disco.
There are a lot of young people around, playing soccer on the street, swimming in the river, strolling with their friends. Poster promotion of safe sex largely focuses on teenagers, and condom dispensing machines are displayed prominently on the streets. For diversion, we go to the races. The track is marked out with plastic tape and curves so tightly that races have to be run off in heats, two horses at a time. In the feature event of the day the front-runner leads until the last lap; then the horses disappear behind a grove of trees and the other rider emerges in front. The loser claims skulduggery, because no sooner have jockeys and owners made their way to the circle of trucks which form the enclosure than a row breaks out. The crowd begins to filter in the same direction when people realise something's up, and in no time at all there's a melee.
The squabble is forgotten by evening, and anyway one of the most popular entertainers in the country is playing in town tonight. After a brief warm-up by the band, Marco Paulo arrives onstage and launches straight into a Tom Jones' classic. And a packed square - children, teenagers and parents - chants the chorus: "Why why why, Delilah?"
Every town and parish has a summer festival, usually devoted to its patron saint. Parades of religious piety and regional customs come together in a spirit of carnival, and are deeply embedded in local tradition. The Festas Gualterianas in Guimaraes has run annually since 1452, but then Ponta da Lima's "New Fair" dates from the 12th century.
Further east, the lush river landscape rises into the dry, stony mountains which lead into Spain. A vast territory of fir-covered mountains and steep gorges, lakes and waterfalls, the area is a national park with its centre at Gers, a spa town which has been fashionable since the last century.