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Aerial photo of Old Harlem showing the newly found ancient Dutch castle      Source: Saricon / NHNieuws

Rare Ancient Dutch Castle is Bigger and Better than Expected!


The Netherlands isn’t known as a country that announces archaeological discoveries every week. However, there are countless ancient sites of medieval interest in the Netherlands, ranging from Anglo-Saxon holy wells, churches, cathedrals and missionaries, to stone landmarks commemorating medieval murders. But one find, hidden beneath the country’s medieval top soils, according to a news report by Holland daily, NH NIEUWS , marks the discovery of an ancient Dutch castle, and it is the oldest example of its type found in the Netherlands.

In an email to Ancient Origins, the researchers said that after a year’s work at the site they have discovered that the ancient castle is even bigger and better than they first expected. “This castle was the biggest and most advanced castle in the Netherlands during its period of existence (1248-1351),” they said.

3D model of the castle grounds. (SARICON)

The ancient Dutch castle was found on the grounds of Oud Haerlem castle in Heemskerk, Netherlands. The archaeologist who identified it, Nancy de Jong, said she “cannot believe her luck” after making this exceptionally rare find.

Oud Haerlem comprises the ruins of a former castle located on the east side of Heemskerk town, about 400 meters (1312.34 feet) southwest of Slot Assumburg. Oud Haerlem castle was built in 1248 AD by Simon van Haerlem.

It was destroyed in 1351 AD during the Hoekse and Kabeljauwse disputes (Hook and Cod wars), which were a series of battles that took place in Holland between 1350 and 1490 AD. The battles were fought over the title of “ Count of Holland .” The castle was rediscovered in the 1930s by aerial archaeologists.

Area of land where the newly discovered ancient Dutch castle is located  (Gemeente Heemskerk / YouTube Screenshot)

Area of land where the newly discovered ancient Dutch castle is located  (Gemeente Heemskerk / YouTube Screenshot )

Newly Found Dutch Castle: A Classic Castle With Towers

The ancient Dutch castle site was first examined in 1960 by Professor J.G.N. Renud, who excavated parts of the castle remains and mapped the outer castle. At that time Bronze Age artifacts were discovered at the site dating back to the 14th century. In 2016, a series of irregular elevations were observed in the meadow surrounding the former castle.

When these features were examined, unbeknown to the archaeologists, they were only a few meters from the buried second castle that was recently discovered by archaeo-geophysical specialist Nancy de Jong and the team. Dr. de Jong said:

"We knew that there was a wall, a kind of city wall, around the site, but not what could still be found inside, and we are very happy that we made such a unique find so quickly - you don't just find a castle in the Netherlands, every day!”

The newly discovered Dutch castle dates from 1250 AD and preliminary surveys have determined that it was destroyed about a century later. As the site has not been developed, the castle remains are well-preserved. And according to Nancy de Jong, when visualizing what this building might have looked like, “this castle reminds us of the classic idea of a castle with towers.”

Image produced using magnetometry and electromagnetic induction revealed the foundations of the newly discovered ancient Dutch castle. (Gemeente Heemskerk / YouTube Screenshot)

Image produced using magnetometry and electromagnetic induction revealed the foundations of the newly discovered ancient Dutch castle. ( Gemeente Heemskerk / YouTube Screenshot )

Ancient Dutch Castle was Part of a Double-Layered Defense

Measuring 45 by 45 square meters (49 by 49 yards) and consisting of several rooms and out buildings, the newly found castle was a square defensive fortress protecting the main Slot Oud Haerlem castle behind it, and this is why stables and sleeping quarters for workmen were discovered by archaeologists within the ruined walls of the new castle.

Until now, archaeologists in the Netherlands had always assumed that the construction of square castles occurred after 1280 AD, during the rule of Floris the Fifth, but this newly discovered example dates from 1250 AD, which pushes back the mainstream archaeological timeframe by three decades. This also makes it the oldest square tower castle type in the Netherlands.

Most Recent Discoveries

The castle was discovered during a geophysical survey undertaken in May 2020, which continued through June 2020. To further illustrate life at the ancient fortress, a non-intrusive soil survey was conducted.

Magnetometry data representation. The continuous lines indicate continuous structures and broken lines are concentrations of rubble. ( SARICON)

The team of archaeologists scanned this 90,000 square meter (10,7640 square yard) archaeological site, and they told us that they found that not only was the ancient Dutch castle more advanced than they first believed, but they also discovered:

  • the defensive structure was much bigger
  • there probably was a tower mill
  • a huge forecourt with impressions of the buildings that were once present there,
  • a very large structure (20x40m), which was probably a tithe barn (tax shed)
  • and a huge tower (18 m diameter) with a 10m tower within it against the first defensive wall

“This is all new information since it's the first time a castle is being explored on such a large scale (90000m2) with geophysics,” the research team told Ancient Origins. The researchers also said that they have created the complete ground plan of the main castle, including the different halls, and are very excited about their discoveries, which make them feel “a little bit like the Dutch version of Time-team.”

The research team consists of: Jean Roefstra (historical archaeologist), Rob Gruben (building historian), Ferry van den Over (geophysicist) and Nancy de Jong-Lambregts (archaeologist, geophysical interpretation).

For the full story on this discovery, watch the YouTube video published by the municipality of Heemskerk, in which the research project leading to the castle’s discovery are explained at length. In this film, Dr. de Jong describes the castle in thoroughly non-archaeological terms, as “really spectacular and very beautiful.”

Who knows? Maybe one day this ancient Dutch castle will become a popular tourist destination for medieval era and Game of Thrones fans.

Top image: Aerial photo of Old Harlem showing the newly found ancient Dutch castle      Source: Saricon / NHNieuws

By Ashley Cowie

Updated on July 21, 2021.

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Ashley is a Scottish historian, author, and documentary filmmaker presenting original perspectives on historical problems in accessible and exciting ways.

He was raised in Wick, a small fishing village in the county of Caithness on the north east coast of... Read More

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