Yes, building a mental map was one of my original motivations for walking from Yokohama to Tokyo. When I did the walk for the first time, in 2006, I was working in Tokyo and had traveled between it and my home in Yokohama hundreds of times, but only by train. I worried that, if I were in Tokyo when a big earthquake struck, I wouldn’t be sure about the best route for walking home. After walking the other direction a couple of times, I stopped worrying about that.

On the day when I could have actually put my newly acquired geographical sense to good use—March 11, 2011—I happened to leave for Osaka a few hours before the quake struck. All of my colleagues either walked home or slept in the office that night, while I had a comfortable hotel room in Namba.

If, on the other hand, you experience Tokyo mostly by train/subway, your mental map is a bunch of islands, and it can be weird when you walk your way from one to another and suddenly your mental compass shifts. For the longest time, I thought the Hachiko crossing was east of Shibuya station, and my mind was blown when I walked to Shibuya from Roppongi and realized I had it backwards.