In his Onomasticon, Eusebius of Caesarea left valuable information for the future generations for locating the major biblical places in the Holy Land. In this monumental work, prepositions, especially pro/s, are of major importance. The present article, primarily based on syntax, discusses the use of the preposition pro/s in Onomasticon. The number of its occurrences, diversity of use, and its relation to specific places attract scholarly attention. The research uncovers that the use of this preposition in Onomasticon does not show discontinuity rather it is in line with its already known functions.