Lasting Impression on the Subway

I was on my way to work on the Glasgow Subway this morning and the carriage was empty. Across from me I could see the impression of a passenger who had been there probably just a short time before me, or perhaps from the previous evening. It then got me thinking of how many people sit on the exact same spot every single day throughout the seats lifetime. The stories it could tell or even the smells that still linger! They are like ghosts of previous passengers...