What often happens to us while travelling is that we stumble upon something exceptionally intriguing. Subsequently, we delve into it to discover that we can find similar constructions in many other places. We then set off to explore these places. What becomes apparent is that although the design is exactly the same everywhere, the shape is different each time. This creates the desire to see even more of these structures, perhaps even all of them. We are far from that point, but having visited 15 of them, we feel that we can write about them. It's about what the Germans call 'graduation towers,' and they are usually found in spa resorts.
When we see spa towns during our travels, we feel drawn to them as if by a magnet. By 'spa towns' we don't mean coastal resorts but places with spa facilities. In German, these places are easily recognisable: their names typically start with 'Bad'. Since March 2009, we have also had one such spa town in the Netherlands, namely Bad Nieuweschans. The most famous of these spa towns can be found in Germany and the Czech Republic. Who hasn't heard of Baden-Baden (one of the oldest spa towns in Germany) or Karlovy Vary (Karlsbad in German) in the Czechia? These spa resorts originated in places where mineral-rich water sources were discovered and where the water was pumped for therapeutic purposes. Since Roman times, these natural springs have been attributed with healing and medicinal properties.
In Germany, salt for household use has been obtained through mineral water sources since 1517 (in ). The history of salt mining can be read in the book 'Alte Saltinen in Mitteleuropa' (Hans-Heinz Emons and Hans-Henning Walter, 1988). Germany has a long tradition of spa treatments; as does Poland. The spa concept as we know it today took shape in the Kingdom of Prussia during the 18th and 19th centuries. It's important to realise that during this period (up until the Napoleonic War in 1815), a part of Poland was part of this kingdom, and even just outside its borders, spa culture was highly popular among aristocrats and intellectuals.
People began to pay more attention to the healing properties of natural springs and sought ways to utilise these sources more effectively for therapeutic purposes. In the Netherlands, there are only a limited number of places with mineral water springs, and we do not have a tradition of spa resorts. There is salt mining in Twente, which began in Boekelo in 1918, after finding saltwater instead of drinking water in the ground near the Twickel Estate in Delden in 1887. You can still experience some spa treatments there because Resort Bad Boekelo seems to still exist. Unlike the coast in South Europe where salt pans are often visible, these salt mines are underground. A mine might sound like salt is readily available, but the salt needs to be extracted from the water.
During one of Jan's journeys, he came across a graduation tower in (Bad Salzemen) near Magdeburg. It's a wooden structure with branches where water continuously flows over. He wanted to learn more about it. In German these towers are called Gradierwerken. The German word 'gradieren' can be translated into English as ‘graduate’, which refers to gradually changing or distributing something into different degrees, steps, or levels.
Let's first paint a picture of a graduation tower. It is a structure consisting of a wooden frame made of oak beams, usually around 10-15m high and ranging from a few metres to hundreds of metres in length. The wooden frame is filled on both sides with bundles of branches, typically branches from the blackthorn tree (known as Schwarzdorn in German). The branches are delivered in bundles and then stacked from bottom to top in the wooden structure. In the past, straw was also used, but dried blackthorn branches last longer, about 5-10 years. Due to the deposition of minerals and dirt, there are unique colour shades ranging from white to deep orange on the branches, and the branches need to be replaced over time. The frame is filled on both sides, and there is often space between the filled frames, sometimes enough to create a path in between. Due to the height of the structure and to ensure that the graduation tower doesn't topple over in a storm, braces are often placed on both sides of the walls. These are inclined oak beams, and the size and number of braces depend on the height of the graduation towers.
This construction is shielded at the top by a wooden floor with a water-guiding structure. On one side of the graduation tower, there is a pump to lift water from the ground. In the past, a windmill was sometimes used for this purpose, beautifully referred to as Windkunst in German. In May 2008, such a windmill was reintroduced to the Neues (new) graduation tower in (Germany), and it functions when there is sufficient wind. The pumped water is directed through channels and/or hollow tree trunks to pipes that, in turn, spray the water into shallow troughs that run the entire length. These pipes can also be closed using a wooden stop if one no longer wants water to flow over a certain part of the branches. The water is then collected and drained underneath the branch structure into wooden containers. The wooden floor on top serves as a cover for the branches to prevent dirt from getting in and for the management and maintenance of the water-guiding structure. The pump is usually covered by a small wooden hut with a roof. In some graduation towers, it is possible to view this structure from the top, for example, in Bad Rothenfelde and (Poland). The latter also has a windmill, by the way.
Well at last, what is the purpose of a graduation tower? The mineral-rich, especially salt-laden water trickles from top to bottom over the blackthorn branches. Due to the sun and wind, a portion of the water evaporates, increasing the salt content in the water. Other minerals and impurities in the water are left behind in the branches; you could say that the water is purified. The salt from this purified water, now with a higher salt content, is then extracted in the salt mine. Despite the closure of many salt mines, you might expect graduation towers to be demolished. However, this is not the case because graduation towers have taken on a life of their own due to the interest in their healing properties and the tourist industry that has subsequently developed around them. You do often see that graduation towers are then shortened.
As a result of the water evaporation, a salt mist forms in the immediate vicinity of a graduation tower. Humidity increases, and with the salt mist, a favourable environment is created for people with respiratory problems. You can imagine that during COVID, this would have attracted a rush of visitors, were it not for the need for social distancing and the proximity of many other people not helping with that. It is said that the microscopic salt particles floating in the air have a beneficial effect for respiratory conditions, such as asthma and bronchitis. People often draw a comparison with sea air. You use a graduation tower by walking around it and taking deep breaths. There are often benches in the immediate vicinity. At some graduation towers, you can walk in the space between the frames, and sometimes there is an inhalation room present. So, around the wooden and branch frame, you usually find walkways and sometimes benches.
Almost all graduation towers are situated in parks or public spaces, making them accessible to the general public. The Gradierhaus, like the one in (Germany), is a part of the enclosed Kurpark. Strolling around the graduation tower is a pleasurable experience, and it naturally heightens your awareness of your breathing. However, you should exercise caution because you may encounter salt splashes on your glasses, clothing, and shoes. Many graduation towers are located in proximity to or serve as the focal point of operational spa resorts. The water that has passed through the graduation tower is subsequently used to fill the baths of these spa resorts or is available in what is known as a Sprudel or water hall where people can draw and/or drink the water.
What captivates us about the graduation towers are the diverse forms they assume and the fact that these structures are still being maintained, refurbished, or even newly constructed. To start with the latter, in , just across the border from the Netherlands in Germany and renowned as a pilgrimage site, you'll discover the Solegarten St. Jakob. It is promoted as a place for "relaxation, rejuvenation, and taking a moment to breathe". In the early 1990s, Dr. Josef Klostermann uncovered a saltwater spring in Kevelaer. This led to the establishment of a graduation tower in 2019 and the inauguration of the Solegarten in mid-2022. What sets this Graduation tower apart is its shape, resembling a St. James' shell with a diameter of 25m and height of 12m. The salt content is 3% before the water traverses the graduation tower and 15% afterward. It is claimed that during the summer, the external temperature inside this graduation tower is 8 degrees lower. Given the present-day summers, this is a delightful advantage. The parks spa experience is further enriched by various baths in the so-called Kneipp-Anlagen. Sebastian Kneipp (1821-1897) from Bavaria is attributed as the discoverer of the therapeutic benefits of water for the human body. The fact that he was a Catholic priest likely influenced the decision to name the baths in Kevelaer after him. Additionally, there is a 'Breathing Path' here: following a winding path, you will encounter 12 distinct breathing exercises, a clever reference to the Stations of the Cross in this Catholic pilgrimage site.
Especially in Poland, but also further in Germany, we observe the construction of new graduation towers exclusively for spa treatments. For this purpose, as in Kevelaer, graduation towers in the form of enclosed spaces with benches inside are often used. This design is more effective for inhaling the salt mist and allows for longer stays. The freedom of design results in highly unique implementations of graduation towers, as seen in and . There are also very small graduation towers that enclose a spring.
It's not easy to determine the oldest graduation tower. All such towers must be rebuilt over time, as the wooden structure becomes too damaged from continuous exposure to water with various minerals and needs replacement. In , it can be quite confusing. There are two Graduation towers: Altes (old) and Neues (new). Interestingly, the Altes graduation tower was the last to be rebuilt, so what is old and new there becomes a matter of perspective?
The Altes graduation tower originally dates back to 1773-1777 when it was 175m long and 13m high. In 1989, a part of it collapsed, and it underwent a thorough renovation from 1994 to 1996, reducing its length to 114m. At the head of this graduation tower, a space on stilts was constructed where diving boards used to be attached, allowing people to dive into the salty water. Due to safety concerns, the deep pool and diving boards were removed, but the structure remains. A unique feature of this Altes graduation tower is that it has a gate through which you can walk approximately from one end to the other. At the top of the gate hangs the clock from the former 1899 saltworks. It used to chime to indicate the start and end of work in the salt mine. When that building was demolished, the clock was preserved and now hangs above the Erpener Gate in this graduation tower. It now only chimes at noon every day. The Neues graduation tower in Bad Rothenfelde was built in 1822-1824, and it is 412m long and 10 high. As mentioned earlier, it has a windmill. It is wider than the Altes graduation tower and features an 80m-long walkway in the middle with an inhalation space.
Let's be clear, the shell shape as in Kevelaer is an exception for a graduation tower, but this graduation tower was not built for salt extraction. All other graduation towers we have seen consist of straight sections, sometimes with multiple sections. The smallest graduation tower we have personally seen is in (Germany). You might mistake it for a pavilion by the architect Rietveld from the Netherlands. Four short sections stand perpendicular to each other but do not connect. This creates a kind of pavilion under a common roof. You can not only walk around these short strips but also sit in the middle of the pavilion. According to a stone near the graduation tower, it has been connected to the Martinsquelle since November 11, 1938.
So, the question arises: what is the largest or longest graduation tower? This is a complicated question. On the internet, we see that the longest graduation tower ever is said to be in – yes, the one that Jan visited first – with a length of 1,837m built in 1756. Due to the cessation of salt mining, many graduation towers have been shortened in length during renovation or restoration work, and this graduation tower is no exception. The largest graduation tower we visited is located in , Poland. Without knowing it, we surprised our friends from Leiden with a visit to this tower and they were in for a treat. It consists of three sections arranged in a horseshoe shape with a total length of 1,741.5m and a height of 15m. The first two original structures were built in 1824-1828, and the third in 1859. The first graduation towers were constructed by Jacob Graff, a professor at the Academy of Mining in Kielce. Ciechocinek is known as the jewel of Polish spa resorts. One of the graduation towers has a windmill, and the water-guiding structure on top can be visited.
What we haven't talked about yet is where graduation towers are located. They are mainly found in former Prussia, especially in present-day Germany and Poland. There are also two in Austria. At the end of this story, you will find an overview of all the graduation towers that we could uncover, totalling 52. We discovered this summer that the information we found on Wikipedia was incomplete. In Bad Wilsnack (Germany), we found a graduation tower that was missing from the list, and the English Wikipedia had a longer list. If anyone else becomes fascinated by graduation towers and finds another one, please let us know because they continue to captivate us.
Would you like to get an impression of a graduation tower through film? Click on the following links:
PS In August 2024, Jan, along with his friend Jan van der Hoeve, discovered another graduation tower, this time in Poland. It is the smallest graduation tower we know of and is still in use. It is located in Bolesławiec
2024
List of graduation towers (53 graduation towers in total, with indication of length or that it's a spring enclosure, the German name of the place, and for the new graduation towers, the year of construction)
Germany (40 graduation towers)
1. (70 m)
2. (330 m)
3. (650 m)
4. (30 m)
5. (bron)
6. (bron)
7. (40 m)
8. (30 m)
9. (70 m rond, 2019)
10. (50 m)
11. ((330 – 258 - 220 – 115 – 60 - 100 m)
12. (310 m)
13. ((4 x 12 m)
14. (60 m)
15. (15 m)
16. (150 m)
17. (320 – 120 – 60 m)
18. (45 m)
19. (70 m)
20. (160 m)
21. (30 m)
22. (200 m)
23. (275 m)
24. (412 - 114 m)
25. (70 m)
26. (bron, 2009)
27. (50 m)
28. (50 m)
29. (160 – 75 – 50 m)
30. (90 – 90 m)
31. (60 m)
32. (bron)
33. (300)
34. (140 m)
35. (50 – 50 m)
36. (140 m)
37. (20 m)
extra (found later): (30m)
38. (120 - 50 m)
39. (60 m)
Poland (11 graduation towers)
40. (730 – 360 – 650 m)
41. (bron, Bad Warmebrunn)
42.(40 m, Köningshutte)
43. (20 m, Gleiwitz)
44. (115 – 95 m, Goldap, 2014)
45. (350 m, Hohensalza)
46. (120 m)
47. (10 m)
48. (25 m)
49. (bron, Istolpmünde, 2020)
50. (150 m)
Austria (2 graduation towers)
51. (bron)
52. (grot)
53. Bolesławiec (small)
