In Bethlehem it’s common to visit the grotto beneath the altar in the Church of Nativity. Here pilgrims can visit the traditional birthplace of Jesus. Historians are now taking note of the increasing amounts of graffiti on the columns that hold the structure up. These columns have graffiti drawn or carved into it that dates back centuries. They are using this to document the pilgrimage some take to the altar each year. This graffiti isn’t a defacement though, most messages ask for forgiveness and show a theme of wanting to leave a piece of them behind at the birthplace. These columns are acting as guestbooks.
Source: Graffiti Documents Pilgrims