These are all over one of the walls at my local train station in London. Anybody know what they could be?
A: I believe those are made by coins. If you put a coin on brick, and twist it, it will eventually make perfect circles like that. Depending on where this is in London, they may have been spending a LOT of time there. The London Underground was used as bomb shelters during WWII, so a lot of people spent a lot of time in those train stations.