Mer.cat de Numismàtica i Filatèlia de la Plaça Reial. Stamp and Coin Market with 36 stalls Sundays on Plaça Reial square in the gothic area of Barcelona. 26 coin stands. 10 stamp stands. Every Sunday from from 10.00 a.m. to 2.00 p.m. Find old stamp and coins from all over the world.