Heemskerk once boasted ten castles. Today, we stand near the site of one of its most intriguing, Kasteel Oud Haerlem.
Kasteel Oud Haerlem’s story whispers from beneath our feet. Simon van Haerlem built it in 1248. Imagine this impressive medieval castle standing proudly. Its walls were erected almost eight centuries ago.
However, its life was not long. In 1351, the Hoekse and Kabeljauwse Twists raged. Kasteel Oud Haerlem became a casualty. It was besieged and destroyed. The castle has been hidden beneath the earth ever since.
Yet, Kasteel Oud Haerlem refuses to be forgotten. Aerial photography in the 1930s rediscovered the castle. The outline of the castle’s structure was captured from above. Its walls and moats became visible from the sky.
Later, in 1960, archaeological investigation began. Professor J.G.N. Renaud led the dig. However, only the outer ward was mapped. A significant bronze treasure was discovered during this work. The main castle was left untouched. It was decided further exploration would wait. They wanted future generations to investigate.
Until recently, only irregular mounds hinted at Kasteel Oud Haerlem’s presence. Some remains were visible at ground level. Since 1977, this site has been a protected national monument.
Then, in 2020, renewed research used modern techniques. Ground-penetrating radar and electromagnetics mapped the site. These methods examined the soil without disturbing it. The entire 9,000 square meter area was surveyed. This revealed the castle’s foundations.
These investigations showed that Renaud only found part of the castle. The 2020 survey revealed the full extent of Kasteel Oud Haerlem. It measured 45 by 45 meters. It dated back to around 1250. It stood for about a century. Because the site remained undisturbed, many remains are still in good condition.
Notably, no other square castle from before 1280 has been discovered. This raises a question. Did Count Willem II, father of Floris V, build it?
In 2021, the data from 2020 was interpreted. Kasteel Oud Haerlem was found to have several features. There was an outer courtyard with dwellings and stables. A main bailey and a forecourt were discovered. It had several moats and a round tower in one of the defensive walls. There was probably also a tithe barn.
Intriguingly, the castle had a square structure. In the 13th century, castles were usually round. Kasteel Oud Haerlem is an exception.
Historians once believed Floris V introduced square castles around 1280. But Oud Haerlem predates this. It challenges our understanding of castle design.
The dig also unearthed that the overblijfselen van Kasteel Oud Haerlem were gewild als bouwmateriaal. Even for Slot Assumburg.
As we stand here, consider what lies beneath. Kasteel Oud Haerlem is a medieval time capsule. Nowhere else in the Netherlands has such a complete castle been found intact in the soil. The stones whisper tales of knights and sieges. They echo with the lives of those who once called this castle home.