The Postojna Gate, less often the Postojna Gap (Slovene: Postojnska vrata), named after the local town of Postojna, is a major mountain pass of the Dinaric Alps. It lies in southwestern Slovenia, between the Hrušica Plateau to the north and the Javornik Hills to the south, at an elevation of 610 metres (2,000 ft). It formed due to tectonic subsidence and fluvial erosion by the Pivka River, which in the Pliocene flew superficially in this section. The terrain is significantly karstified. This relatively wide pass enables for the easiest passage from northearn Italy and northwestern Adriatic Sea to the Pannonian Plain, and had a very important strategic role in the past. Today, a rail line and the Slovenian A1 freeway traverse it.