The pass gives you access to:

The Citadelle Pass is available every day (by reservation for groups). Tours in French, English and Dutch.

It is not possible to book the Citadelle Pass via the online ticket office at the moment.
An advice: book your guided tour of the undergrounds online and buy your tickets for the mini-train and the Visitor's Center on the spot, at the tourist information desk. Only the supplement will be counted towards the price of the Citadelle Pass.
Please arrive at least 30 minutes in advance for the mini-train tour.

Citadelle Pass list of prices