Laura Holt/The Independent. It was this tidal river – Ría de Bilbao – that forced the once industrial city to change its ways, when in 1983 it spilled its banks and caused a catastrophic flood, partly submerging many of the medieval buildings of the Casco Viejo (Old Town).
A few years later, the Basque government began to repossess former industrial land and transform it into something new, with the old shipyards as the focal point. Today, this area, Abandoibarra, is almost entirely made up of modern 20th- and 21st-century architecture. Among its iconic buildings is Frank Gehry's sensuous, rippling Guggenheim Museum (00 34 944 35 90 80 guggenheim-bilbao.es), which is, for many, what put Bilbao on the map in 1997.
A great way of seeing how modern Bilbao has remade itself is by ascending the Funicular de Artxanda (00 34 944 45 49 66;bilbao.net; €0.95/70p one-way). The three-minute journey heaves you up to the top of Artxanda Mountain, which has a small park at the summit. From here, you'll notice that while the Guggenheim stands prominent, it's not the only star to dot Bilbao's skyline.
For a start, there are two other – arguably more impressive – museums to distract your attention. The Museo Bellas Artes (00 34 94 439 60 60; museobilbao.com; daily 10am-8pm, closed Tuesday; €7/£5) proudly displays Spanish painters such as Bilbao-born Alberto Arrúe, while the Basque Museum (00 94 415 54 23; euskal-museoa.org) celebrates the region's culture via 20,000 objects.
Gehry is not the only architectural A-lister to contribute to the city. Norman Foster designed Bilbao's futuristic metro stations, whose eye-catching, glass-tunnelled entrances you'll spot surfacing above the pavements. Santiago Calatrava is responsible for the Zubizuri (White Bridge), and the airport.
The latest big name to join is Zaha Hadid, who has taken on the task of transforming the Zorrozaurre peninsula, beyond the old shipyards, which will be sectioned off into an island, filled with new houses, businesses and recreational spaces. Many consider it "the next Abandoibarra", and teamed with the on-going €1bn project to purge the Ría of all its pollution, is yet more reason for locals to face the river once again.
UNPACK
Boutique Basque (00 34 944 13 48 49; basqueboutique.es) opened two years ago in the Old Town. Run by a local husband-and-wife team, each of the guesthouse's eight rooms is dedicated to a different aspect of Basque culture.
Number 106 has a musical theme in tribute to Arriaga, the Bilbao-born composer nicknamed "the Spanish Mozart", while room 107 has a rustic tone to reflect a typical Basque caserío (countryside dwelling). Doubles from €35 (£25) a night, room only.
THINK LOCAL
At the southern end of the Old Town, La Ribera is a market hall that has stood on this site since 1929. A revamp completed in 2013 gave it a new lease of life, with 60 food stalls selling to discerning locals. Combine your visit with a stop at the new La Ribera Bar (00 34 946 575 474; lariberabilbao.com), whose hip interiors wouldn't be out of place in Brooklyn, but whose food is decidedly Basque, created using ingredients from the market.
EAT
In recent years, Bilbao has developed a dining scene to rival that of San Sebastián. Just across from La Ribera, Michelin-starred Mina Restaurant (00 34 944 795 938; restaurantemina.es) resides in an old mine in the La Vieja neighbourhood. Dishes change daily, depending on what chef Alvaro Garrido can get his hands on at the market. Tasting menus from €55 (£38).
More formal but no less tantalising is Zortziko (00 34 944 23 97 43; zortziko.es), also with a Michelin star. Run by a family of eight brothers and sisters, headed by chef Daniel García, it's located in the new part of town, with tasting menus costing €85 (£70).
DRINK
To sample some of the city's best pintxos bars, head to Calle Licenciado Poza. The rambling street runs up to San Mamés Stadium, the striking new home of Athletic Bilbao, completed in 2013. On match days and weekends, it's a great place to sip local txakoli wine at upmarket spots such as El Gallerinera (00 34 944 277 102); from €3 (£2.17) per glass. Soak it up with typical pintxos such as slices of bread topped with seafood, ham or cheese.
SPEND
The Old Town is a good place to let off some retail steam. Roam around its cobbled streets to find boutiques such as Lula (00 94 416 43 72; lulaonlinestore.com) in Plaza Santiago, which sells vintage-inspired women's clothing, and concept store Cosmos (34 944 15 10 63; cosmosbilbao.com) for art and upcycled furniture at Erronda Kalea 12.
DON'T MISS
Philippe Starck is the man behind the transformation of the Alhóndiga building (00 34 944 01 40 14; alhondigabilbao.com), an old wine warehouse on Plaza Arriquibar that was converted into a public complex in 2010. Today it's filled with exhibition spaces, shops, cafés, a gym and a swimming pool, where you can take a dip for €7 (£5).
GETTING THERE
British Airways (0844 493 0787; ba.com) flies to Bilbao from Heathrow, Edinburgh, and Glasgow. As of today, easyJet (0843 104 5000; easyjet.com) flies from Bristol, along with Stansted and Manchester. Vueling (0906 754 7541; vueling.com) flies from Gatwick.