This weekend marks the 37th annual Open Monuments Day in the Netherlands, when monuments in cities across the country throw open their doors free of charge so people can connect with local churches, windmills, old factories and other familiar landmarks.

In Amsterdam, that includes the grand Keizersgrachtkerk (Keizersgracht Church) and the Fatih Moskee (Fatih Mosque). In Utrecht, people can visit the Dom and Lofen Palace.

In Rotterdam, the Van Nelle Fabriek, a tobacco-factory-cum-events-and-office-space, will open its doors to visitors seeking to learn more about Europe’s first daylight factory, which is also a UNESCO World Heritage site.

But in Groningen, Open Monuments Day has taken a different turn. Its theme is “Living Heritage”, and as part of that, officials are opening the city’s sewers, where visitors can get down and dirty walking through the almost 100-year old sewer pipe Kattendiep and see how the water used to flush the area’s toilets is purified.

The sewage pumping stations on Damsterdiep and Kastanjelaan will also be open to the public, while those heading to the Grote Markt will be able to see what measures are being taken there to prevent flooding.

Climate change

“Water and sewerage affect us all, especially now that rain showers are more intense due to climate change,” said Groningen city councillor Mirjam Wijnja, who will open the festivities by taking a group of visitors down the Kattendiep sewer.

“That is why it is not only visible what the municipality and water boards are doing in this area, but also what residents themselves can do and, above all, should not do.”

“We want to involve people in everything having to do with water and climate,” adds Ronald Rooijakkers, communication advisor to Groningen’s city management.

“They can see how water is used in their daily lives and homes and the harmful effects of things like excessive toilet paper use. It may also help get people thinking about future jobs in water and climate management, where we will need people.”

Toilet humour

The city’s accompanying poster campaign features cheeky images of people shoving their heads into manholes and kitchen sinks with the words, “Where is that going?”

“I think it’s a very Groningen thing to do,” says Groningen native Esther de Jong of the campaign. “People there are very down to earth, but with a lot of humour.”

Now living in Amsterdam, she wishes she was home for the manhole cover-decorated T-shirts being given out alone – although you’ll have to bring your own T-shirts or bag.

But the heat will keep her in Amsterdam, enjoying a local lake. The warm weather indeed runs the risk of putting a damper on other nationwide activities scheduled for Open Monuments Day, which normally draws some 900,000 visitors to about 4,000 sites.

Which just may make Groningen’s sewers, which have been waiting-list-only for the past three years, a very attractive place to be.