It’s a secular cathedral, a cubist ship, a vast glittering shoal of fish… Here, in the atrium of the Guggenheim, huge waterfalls of glass cascade in apparent curves from the ceiling, encasing lifts and stairs. In fact, everything is curved: the walls, the window surrounds, the ceiling, and especially the steel girders that are the armature of the building. Metal walkways snake round above your head. Right at the top, light pours in through windows with criss-cross spars, in contrast to all the other shapes. It takes your breath away.

Designed by Frank Gehry and opened in 1997, the museum was commissioned by the Basque government to revitalise the run-down port area of Bilbao, and indeed the city. It apparently took shape from Gehry’s free, looping line drawings, in which he didn’t lift his pen from the paper. You can see that freedom and fluidity in the shape of the building, seen from across the river. It’s made of steel, limestone, glass and covered in plates, scales, of titanium. They are half a millimetre thick – they give under your touch – and reflect the pink of the city and the sky’s blue. In the largest gallery, (over 400 feet long), Richard Serra’s huge rusted steel sculptures stretch away, eight of them, all over 12 feet high, in circles, spirals, S-shapes – it’s called Snake (or The Matter of Time). You walk between the massive orange plates; whoops and cries echo under the long curved roof.

We go to Café Irun
a on the corner of the Plaza: walls tiled with ceramic bas-relief advertisements for wines and sherries from the early 19th century. Outside, the entrance is solidly blocked by a crowd of smokers, but once through, there’s a space at the bar to drink rioja and eat pintxos – elaborate Basque tapas, bread topped with ratatouille, salt cod, quail’s eggs, anchovies, Iberian ham, cheese – and always the thick slices of tortilla. And more rioja.