CITADEL DIEST

Historical study, building analysis and feasability study for the citadel of Diest



The 19th-century fortification belt around Diest remains tangible today in Fort Leopold, the city gates, the ramparts, and most strikingly in the Citadel. This site is exceptional: it is the only preserved citadel in Flanders and the only one in Europe with an intact Chasseloup-Laubat defense system. Located only 400 meters from the Grand Place and occupying 15% of the city center within the ring road, it represents a rare opportunity to extend the urban core and create a landmark of regional importance.

Although the former military complex is already used by socio-cultural associations, it remains introverted. The ambition is to unlock its potential by developing a contemporary mix of public and private programs, while safeguarding its value as cultural heritage.

The project begins with the restoration of the citadel’s essence: the curtain walls and bastions that frame the central parade square. Later additions such as sheds and halls will be removed. A strong interaction will be sought with the wooded glacis, covering half of the site and acting as a vast green lung for the city. Alongside technical studies (such as moisture remediation), broad workshops are organized with potential partners, including the City of Diest, art academies... New housing may be added within defined limits, and different programmatic scenarios will be tested within a valuation framework. Additional narratives will ensure continuous use and vibrancy.

ALTSTADT’s role in the project proceeds on several levels. On the one hand, we supported the City in preparing an architectural competition for the first phase. On the other, urgent measures are required to prevent further deterioration. While the long-term redevelopment will be defined later, the current strategy focuses on preservation, temporary use, and public engagement, allowing the people of Diest to already discover the site’s potential.

To enable this, essential works are undertaken: damaged walls are locally repaired and protected, broken windows and doors restored, and fire safety and emergency escape routes secured. At the same time, studies on the future roof renovation are carried out in collaboration with the competition-winning architects, laying the foundation for a large urban roof garden—a defining element of the Citadel’s future identity..