The market season opens each year in April with D'r Heëlesje Joarmaat. The next annual market is on Saturday, April 19, 2025 from 9 a.m. - 5 p.m. in downtown Heerlen. It is a large, atmospheric market that brings vendors from all over to Heerlen to sell their wares. Visitors can participate in special activities throughout downtown, wander around 400 market stalls and enjoy art, music and entertainment.