Having started in the Middle Ages, El Rastro is a rambling 3,500-vendor market in the old streets of Madrid. The market begins at 9 a.m. on Sundays and holidays, but gets busiest by 11 a.m. The roughly triangular area runs from the clothing stalls in Plaza de Cascorro, downhill through side streets like Calle San Cayetano (known for its painters), and ends at Ronda de Toledo. The name, El Rastro, is rumored to have come from the trail (or rastro) of blood between the riverside abattoirs and the tanneries on Ribera de Curtidores. Be wary that pickpockets sometimes target market shoppers.