Portugal occupies the western edge of the Iberian Peninsula, with Spain to the north and east along a 1,215 km border and about 943 km of Atlantic coast on the mainland, plus the Azores and Madeira archipelagos far out in the ocean. It covers about 92,000 km². The Tagus River divides the mainland into two contrasting halves: mountains and plateaus cut by deep river valleys in the north, including Serra da Estrela, whose Torre plateau at 1,993 m is the mainland’s highest ground, and the rolling plains of the Alentejo and the Algarve in the south. The country’s highest point is Mount Pico in the Azores, a volcano rising to 2,351 m. The main rivers, from north to south, are the Minho, Douro, Mondego, Tagus and Guadiana; all but the Mondego rise in Spain. Those physical facts explain a great deal about where Portugal’s people live, what they grow and why its border runs where it does.
North and South of the Tagus: A Country Split by One River
Mainland Portugal is mostly low. More than 70 per cent of it lies below 400 m and less than 12 per cent rises above 700 m. But the high ground is almost all on one side of the Tagus: about 95 per cent of the land above 400 m lies north of the river, while in the Alentejo and the Algarve to the south, 62 per cent of the land is below 200 m. The divide shows in the rain as well. Annual rainfall reaches around 3,000 mm on a few mountain tops of Peneda-Gerês National Park in the far north and falls to about 450 mm in the inland Alentejo.
That contrast is the frame for everything that follows. The wet, broken north is Portugal’s land of small farms, dense villages and old towns; the dry, open south is a land of big estates, few villages and long distances. Most of Portugal has a Mediterranean climate, but it is the warm-summer variety north of the Tagus and the hot-summer variety over most of the land to the south.
Minho and Trás-os-Montes: Small Fields in the Green North
The north-western corner between the Minho and Douro rivers, still called the Minho after the former province, lies in the densely populated western half of the Norte region, a land of dense vegetation and small, fragmented farms. In the late 20th century half of the farms in the north were smaller than one hectare and 86 per cent smaller than five. The region is the home of Vinho Verde wine and caldo verde soup, and its towns are some of Portugal’s oldest: Braga began as the Roman Bracara Augusta, and Guimarães grew from medieval Vimaranes. The Iron Age hillfort of Briteiros, the largest Gallaecian stronghold in the region, shows that people were farming these hills long before Rome.
Inland, beyond the mountain barrier that gives Trás-os-Montes (“behind the mountains”) its name, the climate turns harsher and more continental. Winter frosts in the interior north can drop below −10 °C, and the official national low of −16 °C was recorded here at Miranda do Douro as well as at Penhas da Saúde in the Serra da Estrela.
The Alto Douro Terraces and the Port Trade of Porto
The Douro, 897 km long, enters Portugal from Spain’s northern Meseta and cuts a deep valley before reaching the sea at Porto. Upstream, sheltered from Atlantic winds by the Marão and Montemuro mountains, the Alto Douro has hot, dry summers and cold winters. Growers cut terraces into the steep valley sides and planted vines on them, mostly on schist for Port, and the wine landscape became a UNESCO World Heritage Site in 2001.
Trade turned the valley’s geography into a national economy. The earliest known mention of “Port wine” dates from 1675. After the Methuen Treaty of 1703 between Portugal and England, British merchants set up Port lodges in Porto, and a royal charter of 10 September 1756 fixed the boundaries of the production zone, making the Douro the world’s first wine region with a formal demarcation. The vineyards later spread east into hotter, drier country.
Porto itself grew at the river mouth as the Roman port of Portus Cale, the name often cited as the origin of the word “Portugal”. Under Rome it linked Olissipona (Lisbon) with Bracara Augusta. The city proper now has about 273,000 people on 41 km², but its metropolitan area holds around 1.9 million (2025), the second-largest urban area in the country. Its historic centre and the Luiz I Bridge became a UNESCO World Heritage Site in 1996.
Serra da Estrela and the Mondego: Shepherds on the Mainland’s Roof
The Serra da Estrela is, with the Serra da Lousã, the westernmost part of Iberia’s Sistema Central, a granite ridge about 100 km long and up to 30 km wide between Seia, Manteigas, Gouveia, Guarda and Covilhã. Its high point, Torre, is not a peak but the top of a plateau, and it can be reached by a paved road. Ice-age glaciers left small lakes such as Lagoa Comprida and Lagoa Escura, rare natural lakes on a mainland that has no large ones.
The range is a water tower for central Portugal. The Mondego rises here at about 1,425 m in Gouveia municipality and runs 234 km past Coimbra, whose university is a World Heritage Site, to the sea at Figueira da Foz; it is the longest river entirely within Portugal. The Zêzere, a major tributary of the Tagus, also starts in the range. The mountain economy was built on sheep: Queijo Serra da Estrela is made from raw sheep’s milk curdled with cardoon thistle, the local bordaleira sheep are valued for their wool, and the Estrela Mountain Dog was bred to guard the flocks. Today the range is the Serra da Estrela Natural Park, with skiing in Seia municipality.
The Alentejo: Cork Oaks, Land Reform and the Alqueva Reservoir
South of the Tagus, the Alentejo (“beyond the Tagus”) opens into plains and low hills around Évora, Beja and Portalegre. Summers are fierce: Amareleja reached 47.4 °C on 1 August 2003, the official national record. Its characteristic landscape is the montado, open pasture under widely spaced cork and holm oaks, grazed by cattle, sheep and pigs.
This system makes Portugal the world’s largest cork producer; the montado yields roughly half of the cork harvested worldwide each year. Land ownership also shaped politics. After the revolution of 25 April 1974, about 9,000 km² of farmland was occupied in the name of land reform between April 1974 and December 1975, and collective farms were set up across the south. About 32 per cent of the occupations were later ruled illegal, and a Land Reform Review Law followed in 1977.
Water is the Alentejo’s limit, and the Alqueva Dam on the Guadiana was built to lift it. Its floodgates closed on 8 February 2002, and by January 2010 the reservoir had filled to a surface of 250 km², the largest artificial lake in Western Europe, with a shoreline of nearly 1,200 km. The village of Aldeia da Luz, in the flood zone, was rebuilt from scratch on a new site.
A Frontier Fixed at Alcañices in 1297
The land border with Spain is one of the oldest international borders in the world. The Treaty of Alcañices, signed in 1297 by King Denis of Portugal and Fernando IV of Castile, confirmed Portugal’s hold on the Algarve and set the line in essentially its modern form. Rivers carry much of it: the Minho separates Portugal from Galicia in the north, the Douro runs along it for 112 km through narrow canyons, a 47 km stretch of the Tagus forms another section, and the Guadiana marks a long southern stretch before meeting the sea between Vila Real de Santo António and Ayamonte.
One small section remains disputed. Olivenza (Olivença in Portuguese), held by Portugal from 1297, was occupied by Spain in 1801 and ceded under the Treaty of Badajoz that year. Spain administers it and regards it as Spanish territory; Portugal declared the treaty void at the Congress of Vienna in 1815, where Spain undertook to return the town, and does not recognise the border between the Caia river and the Ribeira de Cuncos.
Lisbon, the Tagus Estuary and the Atlantic Islands
The Tagus, the longest river in Iberia at 1,007 km, spends most of its course in Spain and only about 145 km flowing through Portugal before opening into a broad estuary. Lisbon grew on the estuary’s northern shore, and today its municipality has about 658,000 people (2025) inside a metropolitan area of roughly 3.35 million, about 28 per cent of the national population, which Statistics Portugal’s revised 2026 methodology puts above 11 million (about 11.4 million in 2025). West of the city, Cabo da Roca, with a lighthouse operating since 1772, is the westernmost point of mainland Europe. The same offshore geology threatens the capital: the earthquake of 1 November 1755, centred in the Atlantic about 200 km west-south-west of Cape St. Vincent, combined with fire and a tsunami to almost destroy Lisbon, killing an estimated 30,000 to 40,000 people in the city.
Further out, Portugal’s two autonomous regions sit on moving plates. Madeira lies on the African Plate; about a third of Madeira Island stands above 1,000 m, and Funchal, averaging about 20 °C, is the country’s warmest city. The nine Azores islands straddle the junction of the African, Eurasian and North American plates on the Mid-Atlantic Ridge. Mount Pico last erupted in 1720, and on Faial the Capelinhos eruption of 1957–58 added 2.4 km² of new land, destroyed about 300 houses and led some 2,000 people to evacuate, many emigrating to the United States and Canada.
Largely thanks to the islands, which account for about four fifths of it, Portugal’s exclusive economic zone covers about 1.73 million km², nearly nineteen times the country’s area. For more on the archipelago, read our guide to the Azores; for the river that divides the mainland, see our complete guide to the Tagus; and for the trees behind the Alentejo’s landscape, explore the cork oak forests of Portugal and Spain.