Vidago Palace

King Carlos I wanted a thermal spa to rival anything in Europe, built around the mineral waters at Vidago, and commissioned a palace for his family's summers. He was assassinated in 1908. His son Manuel II carried the project on and never used it either. The Vidago Palace opened on 6 October 1910, five days after the monarchy was overthrown and the Republic declared.

It went on regardless, becoming one of the great spa retreats of the Iberian peninsula and filling with European aristocracy who came for the water. It closed in 2006, was extensively restored, and reopened in 2010, a century to the year after it first opened its doors.

The palace is pink, enormous and unapologetically Belle Époque, approached through a park of 250 acres planted with magnolias, camellias and hundred-year-old sequoias, with Art Nouveau pavilions standing over the mineral springs. Inside there are marble staircases, Venetian chandeliers, silk wallpaper and a winter garden with a black and white marble floor where breakfast is served. There are 70 rooms and suites, with high ceilings, hand-painted wallpaper, soaking tubs and balconies.

The spa is the counterpoint. Álvaro Siza Vieira, who won the Pritzker Prize in 1992, designed it as a separate building of white marble and glass, minimal where the palace is ornate, with treatment rooms, hydrotherapy, hammam and pools fed by the Vidago water. Siza also designed the golf clubhouse; the 18-hole course itself is by Philip Mackenzie Ross.

There is a heated outdoor vitality pool, three hiking trails through the grounds, four restaurants and pergolas set up among the trees above the pool.

The important practical point: this is not the Douro. Vidago is in Trás-os-Montes near Chaves, fifteen minutes from that town, half an hour from the Spanish border and about an hour from Porto. The Alto Douro wine region is a substantial drive south. Treat it as a destination rather than a base.

It holds two Michelin Keys and is a member of Leading Hotels of the World. Pets are welcome.