Clashes between Spanish police and anti-globalization activists soured an EU summit that agreed on modest free-market reforms to instil a dose of US-style dynamism into Europe's economy.
Riot police fought running battles with missile-throwing youths after an estimated 250,000 people marched through the Mediterranean port city on Saturday, a few hours after the EU leaders ended their meeting there.
The demonstrators were backing a variety of causes but many of them reject the kind of liberal reforms agreed by the EU leaders, whose main achievement was a step towards opening Europe's electricity and gas markets to competition.
"We're here to say `no' to the European Union, which with each passing day is becoming a model for globalization and is more and more and more like the US in favor of arms and war," said Ada Colau, a spokeswoman for the march organizers.
The bulk of the protest was peaceful but police moved in as young militants, some masked and hooded, set fire to trash cans and threw bottles, rocks and flares. Some banks and storefronts were wrecked and police said they made 38 arrests.
Police said seven officers were injured. Local news reports said six demonstrators and a Spanish news photographer also had to be treated for minor injuries.
Demonstrators disrupted one of Spain's premier sports events -- a soccer match between arch rivals Barcelona and Real Madrid at Barcelona's Nou Camp stadium.
Two protesters, wearing shirts with anti-capitalist slogans, sprinted on to the pitch and attached themselves to the goal posts, delaying the game for over six minutes until they were released. The game was interrupted again later when two Basque nationalist protesters ran on to the pitch.
The EU leaders claimed success in their bid to reinvigorate a two-year-old process of structural reforms aimed at shaking up Europe's energy, labor and financial markets and its transport and education systems to bring European productivity up to US levels.
The leaders agreed to allow businesses to choose their energy suppliers by 2004 but shied away from widening choice for households in deference to French opposition.