FC Porto's Estádio do Dragão, the opening match of Euro 2004 was played there

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sempre contra a corrente do jogo

I guess if we're talking football (soccer to us Americans), then it would have to be Columbus Crew Stadium. It's nothing special compared to those European monster stadiums, but it's a nice place to watch a game, and it's walking distance from my house. It's also the first stadium in the US built primarily as a soccer stadium.