One day, on my commute to work, I wondered – "How deep underground am I?" Escalators, stairs, lifts, mazes of tunnels… no idea. I searched the internet – a few people have done curiosity maps and played with Beck's design, so surely one of depths must exist. Trawling the internet, seeking to satiate my curiosity, I found nothing. So my curiosity turned into a mission – I would create these. I set on to research and got an excel sheet from TfL.

Taking a page from Beck's book, I couldn't represent distances between stations to scale, as that would have render most diagrams impractical. The only accurate scale would be that of depth. I created the first diagram – the Victoria line, one of the simplest. Once I got on to the Central line I realised my approach had to change – some lines have different branches, and as the diagrams represent a unique path, I couldn't create a single diagram for the whole line.