The Spanish stay up late. It can be "very early" at 2 in the morning, at 3.... I've been told "Es muy temprano" at 4:30 more than once.
A friend of mine in Seville had moved there from Madrid because the air in Seville is cleaner. She had some complaints about the city she considered it a "pueblo," or "village," and culturally backward. One of her particular criticisms was that everything is closed far too early. The first time she said it was after work one evening, and after a night of some beer and cigarettes at 5:30 in the morning.
(The Spanish even have a word for the period of time that is niether "la noche" [night] nor "la mañana" [morning] but "la madrugada.")
We did find one place, though. Somebody told us about it as he was having us leave his bar at about 3:30. It's up around the corner, he said turn left and then another left. Up a narrow road and then another. We found a closed door. Eugenia pressed a buzzer.
The barman let us in, and served us beer. I felt slightly uncomfortable, since I didn't want us to keep him from going home. We were the only ones there.
A large dog traipsed in a lugubrious fashion behind and in front of the bar.
Not knowing the culture and not speaking Spanish well, I assumed of course that the barman was just finishing the last of his cleanup (the place was spotless, after all,) and that he was being kind enough to let us have a last beer.
But another patron showed up, joined in conversation, and got a beer... and then another... and more people.... The place was just opening.
Bar El Mundo, Seville. I don't know the address of it. Nearby Plaza Alfalfa. Opens at 3:30. At that hour, the night is young.
I lived in Seville from December 2000 until June 2001.