One day, not too long after we'd started living in Berlin, Sasha was catching the U-Bahn home to where we were living at the time and we were chatting on our phones while she waited for the train to show up. "A train just came through" she told me as she interrupted our conversation topic, "its not like the normal trains". I responded that it might be one of the maintenance trains and she said no - it had people on it in open topped carriages with hard hats on and they all looked embarrassed to be sitting there. She also said there was signs on the side of the carriages with a name beginning with C. This all sounded most bizarre, I couldn't think of what it might be - some kind of engineering inspection train? people seeing the system as part of some Engineering conference? Then I found the website about it - it was called a Cabrio tour, and it was a tour of Berlin's U-Bahn system by open-top train. You would never be able to do this in London! It only ran once a month, in the evenings and only in the summer months - it wasn't cheap either, at €50 but guess what - there was only 1 more trip for the year and it was sold out. In fact, advice online seemed to indicate it would sell out in short order as soon as tickets became available, typically in January.
So, in January, I managed to book two tickets near the end of May to ride the Cabrio - it was the last date where I could book the earlier of two evening trips before we potentially might be leaving Germany. Quite a long way into the future to plan, but that was the way it had to be! Eventually the Friday in question rolled around - it just so happened to be the same day that we needed to move house, from Janine's where we'd been for nearly 3 months into our friend's Sandra & Christian's place where we were house sitting for 6 weeks while they holidayed in America. That move was accomplished a lot easier than we expected, and we showed up at the designated station to take our Cabrio ride around the Berlin Underground system over the course of 90 minutes.