Surrounded by deep moats and accessed by a drawbridge, it consists of a masonry wall (scarp), topped by a chemin de ronde, or covered path for musketeers.

The garrison of about 200 men had access to various galleries, including two large ones underground that connect the central courtyard to the parapets.

Built on a six-hectare site, the Fort du Questel dominates the valley of Allégoet, a tributary of the Penfeld.

This site is now part of a set of refurbished natural spaces that lead to the banks of the Penfeld by a track passing in front of the Cavale Blanche hospital.

Onsite, the fortress offers walks through its sheltered green moat and its underground galleries, staircases, scarps and counterscarps, esplanade and fresh greenery nearby.