Ajdovscina ( Italian: , German: ) is a small town with a population of about 6,700, located in the Vipava Valley (Vipavska dolina), Slovenia. It is the administrative centre of the Municipality of Ajdovscina.
The first mentions of Ajdovscina go as far as 2000 BC. In the Bronze Age and the Iron Age a fortified settlement stood on the nearby hill of Gradisce. In the early period of the Roman Empire, after a road was built from Aquileia towards Emona, a small post and goods station known as mansio Fluvio Frigido stood on the site of todays Ajdovscina.
In the late 3rd century and the early 4th century a fortification system, Claustra Alpium Iuliarum, which run from the Kvarner Gulf to Cividale, was built by the Roman Empire. Its centre was the fortress of Castra or Castrum ad Fluvio Frigido, the remains of which are today still visible in Ajdovscina.
Despite the fact that the Italian border is less than 20 km away and that Ajdovscina was under Italian administration from 1918 to 1945, and from 1927 as a commune of the Province of Gorizia (as Aidussina), during Italian rule (1918–1943, nominally lasted to 1945), the style of the town does not resemble that of a typical Italian town. The strong bora winds would cause damage to the usual Italian house construction. Thus the population adopted and modified the classical Karst architecture for their own needs; for example, by putting stones on roofs to weight down the tiles against the strong winds.
After World War II Ajdovscina became the economic and cultural centre of the upper Vipava Valley. Major industries include textile fabrics, construction, food, beverages, and furniture.
Ajdovscina annexed the formerly independent settlement of Sturje in 1953.
The Hubelj River is the dividing line between the two largest parts of Ajdovscina, locally known as Sturje and Ajdovscina. During the pre-World War I years the river was also the border between the Austrian lands of Gorizia and Gradisca and Carniola.
The climate is Mediterranean (minimum temperature in winter ?1 °C (30 °F), maximum 17 °C (63 °F); in the summer time maximum temperature 39 °C (102 °F), minimum 20 °C (68 °F). The town is located around 25 km from the Adriatic Sea.