The smell put me off. I didn’t know it was the Underberg factory at the time. An evil toxic-smelling scent wafted from the lifeless building and a couple of signs outside warned of an “explosionsgefahr” with all kinds of smoking and naked flames very much verboten! The exclamation mark stressed the risk of explosion and the sheer level of verbotenence – very.

I thought it much have been a bomb factory, a dynamite store, or a TNT supply shop. I circled around the building cautiously, noting the ways in, but I didn’t dare enter. I’m the father of two children and did not want to be blown to smithereens. Nobody wants that.

I’d stumbled upon the site by accident after exploring the abandoned Tetra Pak factory beside it. There was no danger of getting blown up there.

This was a bonus find. I only learned it was the Underberg factory when I got home that night to research the Tetra Pak factory. Aha! So that explained the vile smell – Underberg is a herbal “digestif bitter” schnapps or liqueur served in tiny 20ml bottles to try and stop people from drinking too much for their own good. They wouldn’t drink any at all if they could smell the stink of the potion’s creation.

It was first made by Hubert Underberg, who apparently spent years perfecting the brew before launching the product on an unsuspecting public in 1846. Not content with just using whatever local herbs he could find, no, Hubert had to go off and find different herbs from 43 different countries! Germany wasn’t one of them as it didn’t exist at the time. The rival sovereign states that would form the country weren’t unified till 1871.

It begs the question which countries were in fact represented in this wonderful herbal union, how many of them still exist, and indeed, if 43 different countries are still bottled in this way. You’d also have to wonder why Hubert couldn’t just get the damn herbs he needed and grow them in his garden. It couldn’t be a marketing gimmick, oh no!

Apparently, only five people know Hubert’s secret recipe. What a tragedy it would be if something should befall all five of them at once! No wonder the factory in Heiligensee was taking so many precautions with the coronavirus. As well as the signs warning of potential explosions, there are still plenty of signs up urging people to wear face masks if they want to enter the premises.

Strangely, Underberg makes no mention of the Heiligensee plant on its website. It’s as if the distillery never existed at all. It only talks about Rheinsberg in the west of Germany as if that’s the only place Underberg was ever made since Hubert first flung 43 herbs into a bucket and wondered if he could convince people to drink it.

But Underberg was also distilled in Berlin, spending eight months in 24 barrels made of Slovenian oak that were apparently 100 years old. No other country’s oak would do, no other aged barrels would suffice, of course. Those 43 herbs are picky!

“The rows of small, wrapped bottles that are filled in the production lines of the Berlin Underberg plant are endless. There are 70,000 every hour,” Katja Fischer wrote for Welt in 2003. “One million of them leave the plant in Heiligensee every day.”

Fischer wrote that Underberg had a presence in Berlin since 1886 and had been producing its potion in the city since 1962. The Heiligensee factory was built in 1977.

Other drinks were bottled there too, including Boonekamp – another small-bottled herbal brew (with 45 herbs!) stocked beside the chocolates and condoms at German supermarket checkouts – as well as Pitú cachaça, Sangrita and Unicum. The latter doesn’t sound too appetizing either, but apparently it’s another herbal liqueur, this time from Hungary. Like the others, it’s made from more than 40 herbs to a secret recipe. They’re probably all from different countries, too.

All the bottling and brewing came to an end in 2021, when Underberg finally left the premises under pressure from local politicians who still want to replace it and the neighboring Tetra Pak factory with housing.

The only herbs in the Underberg factory now are the ones sprouting from the roof, which has convenient holes in it for birds to come and go. They’ve overcome the stench to set up their own little homes above the wide, open floors. They’ve seen everything. If you want to know the secret recipe, just ask them.

• What: Abandoned Underberg factory.
• Where: Hennigsdorfer Str. 165, Heiligensee, 13503 Berlin.
• How to get there: Heiligensee S-Bahnhof is just around the corner. The S25 goes every 20 minutes. Here it is on a map.
• Getting in: Go into the Aldi parking lot and pass the store on your right. When you get to the Underberg factory gate, simply swing around the fence on the left-hand side, beside the Tetra Pak factory, where the two factories meet. Once you’re on the grounds, walk down the roadway and you’ll find an opening into the factory on your right. There is also an open door at the back of the factory.
• When to go: Daytime is best for exploring, nighttime if you want to have a party. Just don’t make it too wild or the nosy neighbors will call the Polizei.
• Difficulty rating: 2/10.
• Who to bring: Witches, wizards and any other herbal potion experts.
• What to bring: Bring your own drinks as there are none on site anymore – not that you’d want to drink there if there were. Bring your camera, torch and snacks. The local Späti is abandoned so you won’t be able to get anything there.
• Dangers: You need to watch where you step, but otherwise you should be fine.