This brings to my mind the rune graffitis found on the Hagia Sophia mosque: https://en.wikipedia.org/wiki/Runic_inscriptions_in_Hagia_So...

At the time the graffiti was carved, it was a church and the carver was likely a Viking mercenary in the Varangian Guard.

Seeing it a few years ago was a very strange feeling. It is both small and inconsequential as a thing, yet making me feel deeply moved and making me think about and connect somehow with history in a way that a statue of an emperor does not.