Cool Market!
The Mercado de los Motores is held the first weekend of every month in an old building near the Pacifico and Menendez-Pelayo metro stops (Line 1) in south-central Madrid. Despite the name, the market has nothing at all to do with cars. The name comes from the building, which used to house the power generators for the Madrid Metro network until the 80s when it was decommissioned. The building is gorgeous, and the power works are pretty impressive (you can visit them on normal days if you like), but the real reason for coming here is the Mercado de los Motores!
The marketplace is basically divided into three sections. The first is inside the old power works: here, you find higher-end boutique designers and handicrafts, things like vintage clothes, artisanal soaps, hand-made bags, hats, iphone covers, espadrilles, scarves, and more. The second (and my favorite), is found outside, where normal people come to set up shop and the place takes on more of a flea-market vibe. You can literally peruse for hours, checking out all kinds of vintage jewelry, bicycles, clothes, decorations, and knick-knacks: everything from original Russian-language film posters to vintage Fred Perry polos (for 10euros!) to DVDs to some awesome furniture made out of reconditioned shutters from old buildings.