Photo taken on Dec. 8, 2019 shows the "make a wish" balls on Christmas trees at the "Christmas Market Municipal Cave", an underground Christmas market in Valkenburg, the Netherlands. The Christmas Market Municipal Cave is held in the marlstone corridors of the Municipal Cave in Valkenburg in the southeastern Netherlands. The market lasts from Nov. 15 to Dec. 29 this year. (Xinhua/Lin Liping)