St. Peter and St. Paul etching containing a Chi-Rho
Based on Wikipedia content that has been reviewed, edited, and republished.
Original image by Anonymous. Uploaded by Paul De Mola, published on 09 May 2013 under the following license: Creative Commons: Attribution-ShareAlike. This license lets others remix, tweak, and build upon your work even for commercial reasons, as long as they credit you and license their new creations under the identical terms.