The Douro is one of the longest rivers in the Iberian peninsula flowing across north-central Spain and through Portugal to Porto where it meets the sea. For 112 kilometres of its 897 length, it forms the national border between the two countries. In Spain it passes through a number of major towns including Soria, Tordesillas and Zamora as well as farmland and vineyards. It is only in Portugal, however, that is navigable by rivercraft. Here, except for Porto and Vila Nova de Gaia, the region has a low population and the area is given over in great part to the vineyards that grow the grapes for port.

Some say the name “Douro” means “gold”, making this the Golden River, reflected in the endless sunny days of summer and villages made of stone as honeyed as the Cotswolds. Others say the spelling is really “Duro” or “hard”, referring to the time when treacherous rapids, floods and droughts made the river almost impossible to navigate.Its colour certainly shows no hint of gold. It is the deepest green, from the reflection of the trees along its banks. And, above the trees, stretching up hillsides that reach mountainous proportions are the vineyards. They cover every scrap of land, positioned in rows that are horizontal, vertical and diagonal and create a massive patchwork quilt that covers this entire landscape. And it is the vineyards that define this region because this is port country. Porto is the biggest town and a UNESCO World Heritage site with traditional tall terraced houses painted yellow, pink or blue or covered in the tiles, azulejos, that were the heritage of the Moors. Itfaces Gaia, the place where the great port houses have their cellars – Sandeman, Dows, Taylors, Croft – and you can take a tour past massive oak barrels and bottles covered in cobwebs – and, of course, finish with a tasting.