The "Holland 4 Days Cross Marches Nijmegen" likely refers to the International Four Days Marches Nijmegen, also known as the Vierdaagse. It's an annual event in Nijmegen, Netherlands, where participants walk 30, 40, or 50 kilometers daily for four consecutive days. The event attracts over 45,000 participants from various countries, spanning a wide age range. Participants can earn the Cross for the Four Day Marches (Vierdaagsekruis), a prestigious award given upon successful completion of the march.