The Hotel Londres is one of San Sebastián's poshest hotels. Forget about that. Sneak in through the side door, and follow the signs for bingo. Sit back in the comfy chair, around a table with a video broadcasting numbered plastic balls, and get ready to shout Bingo.
It's not the coolest scene in town, but it is one of the most, err, authentic, and the waiters are authentic, the wine ain't bad, and you have the chance of a decent ROI. And it's a whole lot of fun.