One of the cool things about living in Nijmegen is that every year they host the Four Day March (http://www.4daagse.nl/en/). The International Four Day Marches is the largest marching event in the world. Participants walk 30, 40 or 50 kilometers daily depending on their age and gender. The participants are mostly civilians, but there are a few thousand military participants.
In addition to the walk, there are a lot of food vendors, music and people that come to enjoy the festivities.