Janus was also involved in spatial transitions, presiding over home doors, city gates and boundaries. Numerous toponyms of places located at the boundary between the territory of two communities, especially Etrurians and Latins or Umbrians, are named after the god. The most notable instance is the Ianiculum which marked the access to Etruria from Rome. Since borders often coincided with rivers and the border of Rome (and other Italics) with Etruria was the Tiber, it has been argued that its crossing had a religious connotation; it would have involved a set of rigorous apotropaic practices and a devotional attitude. Janus would have originally regulated particularly the crossing of this sacred river through the pons sublicius.