Access to the grounds of the Citadel is generally free. Exploring the city's fortifications (e.g., walking the ramparts) is also free.
For the **Citadel of Den Bosch**, there is typically no entrance fee to access the exterior grounds and perimeter. Visitors can walk around and view the fortress freely.
Similarly, exploring the **city's historical fortifications**, such as walking along the ramparts or canals, is a free activity. There are no ticket requirements for these public spaces. Some specific museums or attractions located within or near the fortifications might have their own entry fees, but access to the historical structures themselves is free.