Each year, the Heritage Days invite the curious to push open doors of places that are often closed for most of the year or to rediscover iconic sites with a fresh eye. For this 2026 edition, which will take place over the weekend of September 19 and 20, the Château de Montagu, in Marcoussis in Essonne, will once again open its ruins to visitors, offering a chance to trace several centuries of history in the Île-de-France region.
Built in the early 15th century by Jean de Montagu, the royal finance minister under King Charles VI, the château began as a formidable fortress designed as much for show as for defense. With its ramparts, towers, wide moats and meticulous architecture, it stood among the era’s most striking achievements. Over the centuries the estate evolved, hosting several sovereigns, including Henri IV, before being gradually abandoned and largely dismantled in the 19th century.
Today, the ruins of the castle still bear witness to this rich history. The spectacular Henri IV Tower, the only medieval tower still standing, has become the emblem of the site. Long weakened by time, it underwent a major restoration project carried out thanks to the mobilization of many volunteers, as well as public and private partners, and the 'Association Historique de Marcoussis, which has been working for more than thirty years to preserve and bring this local heritage to life.
Open House at Montagu Castle
Montagu Castle
Open doors at Montagu Castle. A briefing on the restoration work and a tour of the freshly restored Henri IV Tower.
Participation requirements: Maximum 20 people per tower visit - Free | No reservation required
Hours: Saturday, September 19, 2026 — 10:00 AM to 5:00 PM | Sunday, September 20, 2026 — 10:00 AM to 5:00 PM
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Dates and Opening Time
From September 19, 2026 to September 20, 2026
Location
Chateau de Montagu
53 Avenue Massenat Deroche
91460 Marcoussis
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