Gigantic radomes tower over dozens of graffitied walls at Teufelsberg. Business Insider/Sam Shead "What shall I do this weekend in Berlin?" I asked a local technology journalist at the end of the Noah Berlin technology conference last week.

"Go to Teufelsberg," he replied confidently, before going on to explain that Teufelsberg is an abandoned listening post in West Berlin that the US National Security Agency (NSA) once used to intercept East Berlin and Soviet communications during the Cold War.

Finding the site wasn't easy. My travelling companion and I took a 20-minute train from central Berlin to Heerstraße station. From there we used Citymapper and ended up hiking a barely-visible trail through relatively dense forest for around half an hour.

We reached a double fence that blocked the way. Fortunately, there were a few unofficial-looking A4 paper signs attached to the outer fence that pointed us round towards a vague-looking entrance, some 400m away.

I'd read mixed reports about Teufelsberg online and I wasn't sure whether we'd even be able to get in as the site has opened and closed several times since the NSA left following the collapse of the Berlin wall in 1989. Some people were saying online that you had to pay, while others said you could simply find a hole in the fence and climb through. One thing most people appeared to agree on is that this place is quite unique and after paying it a visit, I have to say, they're not wrong.

Here are a few photos from the visit: