Which Roman god protected boundaries and boundary markers?

The Roman god who protected boundaries and boundary markers was Terminus. His name was also the Latin word for a boundary or boundary stone, making him one of Rome’s most concrete and place-bound deities.

Roman landowners honored Terminus through the Terminalia, an annual festival held on February 23. Neighbors decorated opposite sides of a boundary marker, offered crops, honey, wine, and sometimes sacrificed an animal, then shared a communal meal. The rituals treated the marker itself as the god’s physical presence.

A famous tradition placed a stone of Terminus inside the Temple of Jupiter Optimus Maximus on the Capitoline Hill. Because the stone was believed not to be moved, an opening was left in the roof above it. Ancient writers linked Terminus’s introduction to the reigns of Romulus or Numa. Janus governed passages and beginnings, while Silvanus and Faunus had different rural associations.