The door of a centuries-old church that normally remains closed. The sound of a turning waterwheel. The ruins of a castle where the walls still bear the scars of war. During Open Monument Day on Saturday 12 and Sunday 13 September 2026, you’ll have the chance to explore heritage sites up close at all sorts of locations across North Limburg.
You can discover these seven heritage sites in North Limburg during Open Monument Day 2026:
- Heijen Castle: a moated castle that has been rebuilt
- Mookerheide Estate: from Art Nouveau to a historic vegetable garden
- Gennep Old Town Hall: step into the story of 1641
- Bleijenbeek Castle Ruins: literally step into history
- Church tour of Venlo: three churches, three very different stories
- Take a look at Venlo Town Hall in the midst of its restoration and combine this with other locations
- Bovenste Plasmolen: see and hear the watermill at work
What exactly is Open Monument Day?
Every year, on the second weekend of September, thousands of historic buildings across the Netherlands are open to the public free of charge. This is also the case in North Limburg. You’ll gain access to places you’d otherwise often walk right past and hear stories from guides, millers, volunteers and other experts. This year is particularly special. Open Monument Day is celebrating its 40th anniversary, with the theme ‘Resilient heritage, in times of uncertainty’. We’ve put together a list of some special places to visit on 12 and 13 September.
1. Heijen Castle: a moated castle that has been rebuilt
Huys Heijen, better known as Heijen Castle, is a fine example of a building that has had to adapt to the course of history on several occasions. Around 1500, a fortified farmstead was built. Through a series of extensions, the complex developed into a moated castle. The original moats have largely disappeared, but the landscape around the castle still hints at that former state of affairs.
During the Second World War, the castle was severely damaged. After the war, sculptor Peter Roovers bought the ruins and began restoring them. He later used the castle as his home and studio. As such, Huys Heijen fits in perfectly with the theme for 2026: a damaged monument that began a new chapter after the war.
Huys Heijen is not normally open to the public, but will be open from 10.00 am for the event on 12 and 13 September 2026. Would you like to explore the surrounding area after your visit? Then you can set off on the Heijen Loop from Heijen. This walk of around ten kilometres takes you through the area of the old Meuse arm and past Huys Heijen, amongst other places. This will give you a better sense of how the former moated castle fits into the landscape.
Address: Hoofdstraat 38, Heijen
2. Mookerheide Estate: from Art Nouveau to a historic vegetable garden
On Sunday 13 September, from 10.00 am to 4.00 pm, more than just the front door of the hunting lodge will be open at the Mookerheide Estate. You can explore the restored Mookerheide Hunting Lodge, listen to stories from a hunting lodge guide and walk through to the historic kitchen gardens. Activities will also be organised in the surrounding nature reserve.
Be sure to take your time to appreciate the details inside. The hunting lodge was built in the Art Nouveau style at the start of the twentieth century. Inside, be sure to admire the stained-glass windows, the wood carvings and the ceiling paintings. Many of these details were carefully restored during the renovation.
Outside, the story simply continues. The old kitchen gardens, greenhouses and fruit walls were originally part of the estate’s day-to-day operations. Nowadays, vegetables, fruit and flowers are once again being grown there. During Open Monument Day, there will be a vegetable stall, amongst other things, and children can take part in an OERRR craft activity. Anyone wishing to see more of the landscape can also set off on a walk with a forest ranger. An online ticket is required in advance for this excursion.
Address: Heumensebaan 2, Molenhoek
View the full programme
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Mookerheide Hunting Lodge
Mookerheide Hunting Lodge
Nestled amidst the greenery of the Mookerheide Estate lies a unique Art Nouveau hunting lodge dating from 1904. Enjoy coffee, lunch or dinner amidst historic details, walking routes and sweeping views. A place where nature, history and hospitality come together. More info about Mookerheide Hunting Lodge
3. Gennep’s old town hall: step right into the story of 1641
This building alone makes a stroll around the Markt in the fortified town of Gennep well worth your while. The old town hall was rebuilt after the great town fire of 1597 and acquired its distinctive Lower Rhenish Renaissance style between 1612 and 1620. In the centuries that followed, the building served, amongst other things, as a school, a field hospital, a temporary church, a post office, a prison and a fire station.
On the ground floor, you can visit the free exhibition ‘1641: Experience the Siege’. It takes you back to the year in which the Genneper Huys was besieged during the Eighty Years’ War. It is not just generals and soldiers who feature in the story. You’ll also discover what such a siege meant for the ordinary residents of Gennep. The exhibition is open on Saturday 12 September from 10.00 to 16.30 and on Sunday 13 September from 12.30 to 16.30.
Address: Markt 1, 6591 BZ Gennep
4. Bleijenbeek Castle Ruins: literally step back in time
From Paviljoen Bleijenbeek, it’s about a one-kilometre walk to the castle island, home to the Bleijenbeek Castle ruins. On Saturday 12 September, from 11.00 to 16.00, you can explore the site for free as part of Open Monument Day.
Once at the ruins, you’ll walk past areas that aren’t normally open to the public. You’ll see the cellars, which are over six hundred years old, and walk past places where justice was once administered and prisoners were held. Information boards explain what used to lie behind the remaining walls and cellars. There are also volunteers on hand who know the stories behind the ruins.
The Bleijenbeek castle ruins also perfectly illustrate what this year’s theme, ‘resilient heritage’, can mean. For centuries, Bleijenbeek was inhabited, renovated and extended. This came to an abrupt end during the Second World War: the castle was heavily bombed. What remained fell further into disrepair for a long time. The site has now been made safe to the extent that you can walk around it again.
Address: Paviljoen Bleijenbeek, Bleijenbeek 14, Afferden
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Bleijenbeek castle ruins
Bleijenbeek castle ruins
Delve into the history of the Bleijenbeek Castle Ruins. Discover how this castle came to be in ruins. More info about the Bleijenbeek Castle Ruins
5. Church tour of Venlo: three churches, three very different stories
In Venlo, you can easily turn Open Monument Day into a little church tour. St Martin’s Basilica, the Church of the Sacred Heart and St George’s Church are taking part this year. They are not all right next to one another, nor were they built in the same period. That is precisely why it is fun to compare them all in a single day.
Start, for example, at St Martin’s Basilica in the historic city centre. The Gothic basilica has a long history, but also bears clear traces of the twentieth century. The tower had to be rebuilt following the devastation of the Second World War.
The Heilig Hartkerk is still relatively new. The church was built between 1921 and 1926, to a design by architect Jules Kayser. Be sure to take a good look at its shape and façades; they are slightly more playful than those of many older churches in the city. And there’s something striking missing: the planned bell tower was never actually built.
Finish your visit at the Joriskerk, a small church right in the centre of Venlo. From the outside it may look modest, but inside you’ll encounter several centuries of history. More than two centuries later, a Protestant church was built around it. On Saturday 12 September, from 12.00 to 17.00, you can pop in and have a quiet look around for yourself.
St Martin’s Basilica: Grote Kerkstraat 40, Venlo
Heilig Hartkerk: Veldenseweg 2, Venlo
St Joris Church: Sint Jorisstraat 16, Venlo
6. Take a look at Venlo Town Hall whilst it is undergoing restoration and combine this with visits to other locations
We’ll stay in Venlo for a little while longer, as the Town Hall is also taking part. And this year, in particular, a visit is especially interesting. The building is currently undergoing extensive renovation and restoration. On Saturday 12 September, you’ll get a glimpse behind the scenes of this work. On the ground floor, you’ll find information and images about the restoration, and during guided tours you’ll learn more about different parts of the building. During a guided tour, you’ll discover just how much craftsmanship is required to preserve historic buildings. It is precisely this that makes this place so fitting for the theme of Open Monument Day 2026: heritage can only survive if it is properly looked after.
Anyone wishing to explore beyond the churches and the town hall needn’t leave Venlo. During Open Monument Day, the city has an extensive programme featuring several special sites. For example, at De Luif on Havenkade 6a, you can see one of the last remaining sections of the old city wall. Very little of that defensive wall remains, but that is precisely what makes this part of Venlo so special. De Luif has now been converted into a small museum, and guided tours will be available on Saturday 12 September from 11.00 to 18.00.
There is also something to discover underground. Beneath Hospice Mariaweide at 41 Nieuwstraat lie medieval vaulted cellars that serve as a reminder of the former Dominican monastery. You can visit on Saturday 12 September from 11.00 to 18.00. Between 12.00 and 17.00, guided tours lasting around half an hour will depart continuously, with space for ten people per tour.
Address: Markt 2, Venlo
View all monuments in Venlo
7. Bovenste Plasmolen: see and hear the watermill at work
Nestled amidst the greenery of Sint-Jansberg stands the Bovenste Plasmolen. The watermill dates back to 1725 and was used to make paper for over a century. From 1846 onwards, grain was ground and husked there. It is still impressive to see just how much engineering lies behind that large wheel. The mill is unique in that the water can drive the wheel both from above and from approximately halfway down.
On Sunday 13 September, you can pop in between 11.00 and 16.00. The millers will demonstrate how the mechanisms work and explain how the water, via ponds and streams, ultimately sets the wheel and the millstones in motion.
Feel free to turn your visit into a short walk. Both the Kiekberg Route and the Beek Route through Sint-Jansberg pass by the mill. This way, you can see straight away where the mill gets its power from: the water and the difference in height at Sint-Jansberg.
Address: Kiekbergsebaan 6, Plasmolen
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The Upper Plasmolen
The Upper Plasmolen
De Bovenste Plasmolen in Plasmolen is a historic watermill in the nature reserve near the Mookerheide, where you can experience the landscape and history up close. More info about De Bovenste Plasmolen
Frequently asked questions about Open Monument Day in North Limburg
Open Monument Day will take place on Saturday 12 and Sunday 13 September 2026. Opening times vary by monument. Therefore, always check the current programme for the location you wish to visit before setting off.
In principle, the participating heritage sites can be visited free of charge during Open Monument Day. However, for some guided tours, excursions or activities, you will need to book in advance. This applies, for example, where there are only a limited number of places available.
That depends mainly on where you want to go. In Venlo, you can combine a visit to several churches, the town hall, De Luif and the vaulted cellars. Around Mook and Middelaar, the Bovenste Plasmolen and the Mookerheide Estate are beautifully situated close together. In Gennep and the surrounding area, you can visit the old town hall, Heijen Castle and the Bleijenbeek Castle ruins all in one weekend.