Bilbao or Zaragoza?

Bilbao has no beach of its own, but the metro reaches the sands of Getxo, Sopelana and Plentzia in well under an hour. By late summer the Atlantic is warm enough for a proper swim. It makes a beach afternoon rather than a beach trip, with surfers' swell at Sopelana and calmer water in the bay at Plentzia.

Zaragoza has nothing like it. The Mediterranean is more than 200km away and the Ebro isn't used for swimming, so on a hot summer day the choice is a municipal or hotel pool.

Both cities eat by moving from bar to bar, but the standard differs. Bilbao's pintxo counters in the Casco Viejo and the Ensanche are polished even in plain-looking places. Above them are the asadores serving txuleta steaks and a number of Michelin-starred kitchens, and the Ribera market shows off the fish and produce behind it all.

Zaragoza's El Tubo is earthier, with bars that each specialise in one dish such as croquetas, mushrooms or tripe. Add hearty Aragonese ternasco lamb and cheap, generous reds from Cariñena and Somontano. It is honest and satisfying, but fine dining is thin, so food is a pleasure here rather than the reason to go.

The two are evenly matched but strong in different ways. Bilbao's culture is about art and modern architecture: Gehry's Guggenheim, the Bellas Artes collection and the Vizcaya Bridge down the estuary. Its compact old town is pleasant rather than grand.

Zaragoza's culture is layered history. It runs from the Roman forum and theatre through the Islamic Aljafería to the Baroque Pilar, with ceilings painted by Goya, and the Mudéjar walls of La Seo. Choose Bilbao for painting and bold buildings, and Zaragoza for two thousand years of the past in one walk.

Nights out are much alike in both cities. They grow out of the tapas round and keep Spanish hours, and weekends are far livelier than weekdays. Bilbao's late evenings centre on Plaza Nueva and Licenciado Poza, while Zaragoza leans more on its student crowd around Plaza San Felipe and keeps a few more clubs open till morning.

The real difference is the calendar. Bilbao's Aste Nagusia takes over the riverbanks in August, and Zaragoza's Fiestas del Pilar fill the streets until dawn in October.

Bilbao sits in a green valley where the hills start at the edge of town. The funicular goes up Artxanda, the Pagasarri is a half-day hike, and Urkiola's limestone peaks and Gorbea's beech woods are close by. The coast adds cliff paths, Gaztelugatxe and the Urdaibai reserve. Much of it can be reached without a car, and the price is rain.

Zaragoza is surrounded by dry steppe swept by the cierzo wind, and in town nature means the Ebro path and the big parks. Dramatic scenery is out there, at Moncayo, the Mallos de Riglos and the Bardenas Reales, but it needs a car, and the summer heat rules much of it out.

Both make excellent bases, in different ways. Bilbao's outings are regional and close: San Sebastián, Gernika, the fishing ports of the Biscay coast, Vitoria and the Rioja Alavesa vineyards, most of them reachable by bus.

Zaragoza's trump card is the high-speed train, which puts Madrid and Barcelona about an hour and a half away. Around the city lies rural Aragon, with Loarre castle, the ruined old town of Belchite and the Mudéjar towns of Tarazona and Teruel, all best explored by hired car.

Both centres are flat and safe, with families out late, so either works with children. Zaragoza has more made for them: a large river aquarium, the Parque del Agua and a small amusement park. Bilbao has none of that but offers the Artxanda funicular, Puppy outside the Guggenheim and metro rides to the beach. Bilbao's rain and Zaragoza's July heat each call for a backup plan.

Bilbao's public transport reaches much further. A tram follows the river past the Guggenheim and the Euskalduna, Foster's metro runs down both banks of the estuary to the Getxo beaches and the Vizcaya Bridge, and Euskotren and Bizkaibus services carry on to the coast and Gernika. You can see a good deal of Bizkaia without a car.

Zaragoza is simpler. Its sights sit close together between the Pilar and the Aljafería, with one tram line, buses and bike-share for the rest, and Delicias station a short ride out. Once you leave the city, much of the best of Aragon needs a hired car.

Neither city is a shopping destination, and the main shopping streets look much the same, with chains along Bilbao's Gran Vía and Zaragoza's Paseo de la Independencia. The difference is what you take home. Bilbao has Basque berets, espadrilles, txakoli and tinned anchovies from the Casco Viejo and the Ribera. Zaragoza has candied fruit, Aragonese wine and ceramics from Muel.

In Bilbao the difference shows first in the room bill. Hotels cost more than in most Spanish cities, especially near the Guggenheim and during Aste Nagusia, and a sit-down meal at an asador or a starred table is a real expense. The pintxo crawl and the cheap metro keep the rest of the day in check, but these are the parts that cost little in Zaragoza too.

Zaragoza is the clearly cheaper city. The same budget buys a better-placed room, and a full Aragonese meal with a bottle of Cariñena costs much less than its Basque equivalent. The one time to expect Bilbao-level room prices is the October fiestas.

Bilbao has more on stage. The ABAO opera season and the Bilbao Symphony Orchestra play at the Euskalduna, the ornate Arriaga and the Campos Elíseos stage theatre and dance, and BBK Live brings international bands each July.

Zaragoza's Auditorio and Teatro Principal offer reliable concerts and plays, but there is less on. Its special feature is the jota, Aragon's leaping folk song and dance, seen at its best during the Pilar fiestas.

Zaragoza has a slight edge for a spa afternoon. Besides the hotel spas both cities share, it has an Arab-style bathhouse or two, and the thermal waters of Alhama de Aragón are a little over an hour away. Bilbao's nearest equivalent, the old balnearios of the Basque interior, is a separate trip.

The bigger difference is in how you unwind. Bilbao's mild summers suit slow afternoons by the river and evenings drifting between bars. In Zaragoza you get shady hours in Parque Grande and evening strolls along the Ebro, but in high summer the heat and the cierzo can wear you down.