The main flea market in Madrid is El Rastro, which takes place between 9:00AM and 3:00PM every Sunday and on selected holidays. El Rastro can be found in between the La Latina and Lavapies neighborhoods, which are accessible via the metro stations of the same name. The Rastro has approximately 3,500 stalls where you can find anything from clothing to furniture to antiques to books.
On a Sunday morning, the streets leading to El Rastro are thronged with people from the Plaza Mayor all the way to the Puerta de Toledo. If you follow the crowds, you eventually stumble upon the market. Be on your guard while visiting El Rastro as pickpockets are a dime a dozen and work in teams, taking advantage of the fact that you’ll be busy looking at the mounds of merchandise. If you take a backpack with you, wear it in front of you.
Although small flea markets may pop up from time to time in other sections of the city, El Rastro is the only official market.