After Petershagen, our route continued to Bad Oeynhausen, and this was another place whose present appearance makes much more sense once you know why the town exists at all.
Unlike many of the towns we had been passing through, Bad Oeynhausen did not gradually grow over the Middle Ages around a castle, river crossing or market square. Much of the town centre is surprisingly young. Its real beginning lies underground, in salt, hot water and a nineteenth-century drilling operation that was originally looking for something else.
People in this part of Westphalia had known about salt for much longer. Saline deposits were discovered around 1745, and under Frederick the Great the Prussian state developed the Neusalzwerk saltworks. Graduation towers were built along what is now Mindener Straße so that brine could be concentrated before the salt was extracted.
The decisive change came almost a century later.
From 1830, the Prussian mining official Carl Baron von Oeynhausen was supervising drilling intended to locate deposits of rock salt. Instead, the work encountered hot brine rising from deep underground.
What had begun as a search for salt became the basis of a spa.
Von Oeynhausen understood that the warm mineral-rich water could be used therapeutically, and private bathing establishments began using it. In 1845 the baths were taken over by the Prussian state, giving the developing resort an official status.
Three years later, in 1848, King Friedrich Wilhelm IV gave the young spa the name Oeynhausen in honour of the man whose drilling had revealed the springs.
That explains the slightly unusual name Bad Oeynhausen. It does not come from an ancient tribe or medieval noble family that ruled here for centuries. The town is effectively named after the mining engineer responsible for finding the water beneath it.
The spa then created the city around itself.
The Prussian authorities commissioned Peter Joseph Lenné, one of the most important landscape architects of nineteenth-century Germany, to design the Kurpark. Instead of adapting a park to an existing town, Bad Oeynhausen largely developed around the spa gardens.
That is why the central area feels different from many German towns. The broad green park, bathhouses and large villas are not later additions squeezed into an older urban centre. They were fundamental to the creation of the place.
In 1860, the future Emperor Wilhelm I, then Prince Regent of Prussia, ordered the establishment of Oeynhausen as a town. At that point it had only around 1,300 inhabitants.
The railway helped accelerate everything. Wealthy patients could now reach the spa much more easily, and by the late nineteenth and early twentieth centuries Bad Oeynhausen had become a fashionable health resort with hotels, villas and increasingly elaborate public buildings.
The most obvious survivor from that period is the former Kurhaus, completed in 1908 and now known as the Kaiserpalais.
Its exterior looks almost like a palace, which was entirely intentional. Inside, the design took inspiration from the Paris Opera. It was built at a time when a major spa was not supposed to feel like a hospital. Visitors came for treatment, but also for concerts, theatre, social life and long stays in elegant surroundings.
The building now houses the GOP Varieté-Theater, but it still dominates one side of the Kurpark and gives a good idea of how ambitious the old state spa had become.
Then there is the Jordansprudel.
This is the feature that makes Bad Oeynhausen’s underground history visible in a rather spectacular way. The sixth major thermal source was drilled in 1926 and was named the Jordan Spring.
According to the city’s own historical records, it is the world’s largest carbonated thermal brine spring.
When the fountain operates, the water can shoot tens of metres into the air, producing a column high enough to be visible well beyond the immediate park. It is not simply an ornamental fountain supplied by ordinary mains water. It is connected with the same geological system of saline thermal water that created Bad Oeynhausen in the first place.
That gives the Kurpark an unusual centrepiece. The neat paths, lawns and nineteenth-century buildings represent the controlled, elegant side of the spa, while the Jordansprudel is a reminder that the whole town ultimately depends on pressurised mineral water coming out of the ground.
By 1911, the connection with bathing had become so important that Oeynhausen officially became Bad Oeynhausen. In German place names, Bad is not merely a description meaning that a town happens to have a swimming pool or spa hotel. It is an officially recognised designation associated with a health resort.
The old saltworks eventually became unnecessary. Salt production ended in 1928, and the large graduation structures were gradually demolished during the 1930s and 1940s. The spa, however, survived.
Bad Oeynhausen then acquired a very different role at the end of the Second World War.
On 30 March 1945, only days before Allied troops arrived, a heavy bombing raid struck the Weserhütte industrial works. Four days later, on 3 April, the war in Bad Oeynhausen was effectively over.
The British then selected the spa district as an important headquarters.
Large sections of the centre, including much of the Kurpark area, were requisitioned. Buildings that had been hotels, clinics and spa facilities became offices and accommodation for the British occupation authorities. For the local population, this meant that parts of their own town were suddenly inaccessible.
The British headquarters remained in central Bad Oeynhausen until 1954.
That post-war chapter is easy to miss today because the Kurpark has returned completely to its earlier role, but for almost a decade one of Germany’s most famous spa districts was also part of the administrative machinery of the British occupation.
British military connections with the city lasted much longer in other forms. The final elements of British Army Germany did not leave Bad Oeynhausen until 2014.
The town continued to reinvent itself after the spa’s nineteenth-century peak. The Kurpark remained central, but medicine became increasingly important. Bad Oeynhausen is now particularly associated with cardiovascular treatment and is home to the Heart and Diabetes Centre North Rhine-Westphalia, one of the major specialist centres of its kind in Germany.
There is also Aqua Magica, the landscape park created for the 2000 North Rhine-Westphalia State Garden Show between Bad Oeynhausen and neighbouring Löhne. Its most unusual feature again involves the geology beneath the region: a walk-in water crater uses mist, darkness and water to turn the underground world into something visitors can physically enter rather than simply read about.
So water keeps appearing in the story.
First salt water was valuable because salt itself was valuable. Then thermal brine became more important than the salt. That created the spa. The spa created the park. The park encouraged hotels and villas. The railway brought visitors. New springs allowed the resort to expand, and eventually the town became important enough for its entire identity to be built around the word Bad.
For us, coming from Petershagen, that made Bad Oeynhausen an interesting change again. Petershagen had been a town whose history followed an old river and a medieval castle. Bad Oeynhausen was almost the reverse: an essentially nineteenth-century town created because somebody drilled into the ground and found something unexpected.
At first the elegant buildings and enormous park can make it look like a place designed simply to be attractive.
In reality, nearly everything in central Bad Oeynhausen leads back to geology.
The villas, Kaiserpalais, bathhouses, Kurpark and even the name of the town are all consequences of hot salty water rising from beneath Westphalia.