In the center of Amersfoort, standing 98.33 meters tall, is the most distinctive and noticeable landmark of Amersfoort: Onze Lieve Vrouwetoren (in English, “Tower of Our Dear Lady” a common reference to Mother Mary). Not only is the height impressive, being the third largest tower in the Netherlands, but this tower, known as Laang Jon, houses an impressive collection of bells and marks center point for all surveying done in the Netherlands. Read about the history of Onze-Lieve-Vrouwetoren, the carillons of Onze-Lieve-Vrouwetoren, and the Rijksdriehoekscoördinaten.
We visited Amersfoort together with Visit Utrecht Region.
A Brief History of Onze Lieve Vrouwetoren
Onze Lieve Vrouwetoren now stands alone on a square in the city center of Amersfoort. However, there used to be a catholic church of which the tower was but a part. At some point in history, the decision was made to house the city’s stores of gunpowder in the church.
The city lies at the confluence of several rivers coming from the east of the Netherlands, forming the Eem river. Indeed, Amersfoort translates to “the ford of Eem”. Water plays a huge role in Amersfoort’s past, and is also the source of many traditions and superstitions. The city catholics describe all number of water related miracles in the city. Admittedly, The Protestants are bit more mundane in their miracles. As our guide said, “The blind could walk and the lame could see”.
When the gunpowder inevitably exploded, taking the church with it yet leaving the tower, it was one of the last miracles the Catholics ascribed to the city. The protestants, who weren’t known to like the Catholics in this period, also agreed the explosion was a great miracle.
Interestingly, this is not the only time in Dutch history that a city didn’t safely store their gunpowder. A large portion of Delft was destroyed in similar circumstances.
Logistics of visiting Onze Lieve Vrouwetoren
You can purchase tickets ahead on the website if you wish to climb the tower. We purchased tickets about an hour prior to our tour (on a Saturday) after missing the earlier tour that we intended to catch.
The tour was sold out, so purchase ahead or stop by the tourism board office (VVV Amersfoort) to buy tickets. At the moment, tickets can be only purchased with a Dutch card, so bring cash if you don’t have a Maestro card.) A ticket cost 5 euros per adult and the tour took about an hour as we ended up enjoying a carillon concert at the top!
The starting and ending point o the tour is in front of the tower. Our tour was held by a knowledgeable volunteer although our tour was almost exclusively in Dutch with some sporadic translations into English. If you are lucky enough to heard the carilion master and to enjoy the view, it’s still worth it.
The Kadaster and the Rijksdriehoekscoördinaten.
At the beginning of the 19th century, Dutch mathematician Snellius (whose grave you can visit in Leiden), attempted to develop a triangulation of the Earth with the goal of estimating its circumference. His results were the most accurate at the time.
Snellius used many church towers across the Netherlands in order to achieve this triangulation. This served as the inspiration for a unified system of measurement adopted for surveying and tax purposes by the Dutch government nearly a century later.
A government body called the Kadaster was formed to survey the Netherlands an assay lands of individuals for tax purposes. This body still exists and now collects and enormous amount of census and land use data for the county.
Starting at Onze Lieve Vrouwetoren, they drew out as much of the Netherlands as they could see from its peak. From there, they travelled to the highest points on the edges of this drawing and continued drawing outward. Iterating in this manner, they mapped the entire Netherlands and placed it on a grid.
They resulting coordinate system from this grid is called the Rijksdriehoekscoördinaten and its “center” is in Onze Lieve Vrouwetoren. In the base of the tower is a hole in the floor with a picture of the Netherlands below. A laser shines from above pinpointing the exact location of Onze Lieve Vrouwetoren on the map.
The reason that I put “center” in quotes is that the choice was made not to make the center point (0,0) but rather (155000, 463000). This was intended to prevent negative coordinates and to make sure that the smallest y-coordinate always larger the the x-coordinate. That way, if two number were given, you could be sure which was x and which was y.
Additionally, the coordinate system starts from the assumption that the earth is flat. The Netherlands is indeed so flat that this makes the system accurate for much of the country. There are corrections tables near the boundary and the whole system is essentially only valid for the Netherlands. The Kadaster still uses this coordinate system to this day, having resisted a conversion to GPS coordinates.
Carillons in Amersfoort
Carillons are the arrangements of bells of different sizes that one sometimes sees in church towers. They are specifically those designed to be played with a piano-like keyboard and not simply rung.
Onze Lieve Toren contains two distinct carillons, an older set halfway up the tower, and a second set at the top with two different keyboards. One of this keyboards is nearly the size of a full piano, much larger than most carillons. This makes it unique among all carillon towers in the world.
Climbing the tower, you get a chance to learn about carillons and hear them played. We were especially lucky that on our visit, the master carillon player was at the top of the tower and answered our questions and gave us a demonstration.
He explained to us the carillon is a very Dutch instrument, like guitars to the Spanish, and balalaikas to the Russians. The vast majority are in the Netherlands, but quite a few exist in Belgium and France as well.
Amersfoort even has one of the two schools in the world specializing in the instrument, and offers the highest degree. The master carillon player told us that he had actually learned at the Dutch conservatory over the course of six years. As you can imagine, practicing the instrument is a little difficult when the entire town can hear you.
While the carillon has an initial resemblance to a keyboard, pegs must be pulled down rather than keys pushed. Additionally, there are foot pedals to aid in playing the larger bells.
Many carillons were made at a time when musical notes were evenly spaced apart in frequency. In modern times, note frequencies are logarithmic, with an A having twice the frequency than the A one octave below. As such, many carillons sound out of tune to modern ears.
The carillons atop Onze Lieve Vrouwetoren were constructed around 2000 with the modern tuning and are played regularly in the town. We were told the how long a bell rings after being struck is a sign of quality. We listened to one of them ring for two minutes.
The ability to play bells both loudly and softly relies on a system of springs with control the bell clappers. The system was actually invented by famed Dutch physicist Christiaan Huygens. However, there are no dampeners on a bell to silence it after it is rung, so music must be arranged specifically to accommodate the instrument. Otherwise, one risks a cacophony of overlapping notes.
We have climbed many towers in many countries and at some point one thinks you’ve seen it all. Not to say we avoid it as we still enjoy the view over the city one gets from above. But we were delightfully surprised at how interesting and fun our tour of Onze Lieve Vrouwetoren was and it was one of the highlights of our trip to Amersfoort.