Fort du Trou-d'Enfer

Fort du Trou-d'Enfer is a fortified complex located in Marly-le-Roi that sits on wooded terrain and features thick stone walls with multiple defensive structures. The facility includes a central courtyard surrounded by various casemates and defensive trenches.

The fortress was constructed between 1878 and 1881 as part of Paris's defensive system. It served as an important component of French military infrastructure during that period.

The grounds were later converted into a pheasant breeding facility for presidential hunting, a use that continued until 2010. Visitors can still see traces of this unexpected purpose scattered across the property.

Access to the fortress is typically through organized guided tours that must be arranged in advance. Wear comfortable shoes as the grounds are uneven and include several walking paths to explore.

The fortress has two underground powder magazines connected to the main barracks through covered passages. These hidden structures reveal the strategic planning behind the military complex.

Location: Marly-le-Roi

Location: Bailly

Elevation above the sea: 178 m

Part of: Fortifications of Paris in the 19th and 20th centuries

Address: route de Maintenon 78160 Marly-le-Roi

Website: https://memoire-et-fortifications.fr/fortifications/place-forte-de-paris/le-fort-du-trou-d-enfer-grande-guerre-paris

GPS coordinates: 48.84907,2.08656

Latest update: December 15, 2025 09:21