The Municipality of Miren-Kostanjevica on the west borders the Republic of Italy, on the north the Municipality of Šempeter - Vrtojba, on the east the Municipality of Nova Gorica and on the south the Municipality of Komen na Krasu. It comprises 15 settlements and its administrative centre is Miren.

Its region is very diverse. The part called also the "Goriška garden" extends into the Vipava Valley. It is covered by fertile fields, gardens and orchards, among which the Vipava river is winding. The rest of the region penetrates the Karst region and is characterised by a colourful and diverse Karst flora with sinkholes and deep abysses challenging many cave explorers. This is the home of Karst prosciutto and Teran.

Miren is famous for almost 100-year shoe making tradition, Bilje for its brick-making and Kras for stonecutting.

The present-day settlements in the Municipality of Miren-Kostanjevica date back to prehistoric times and Antiquity. This is proved by numerous archaeological sites of prehistoric forts and Roman burial grounds at Miren and Bilje. The most appealing tourist sites in the Municipality are: Miren Castle with the pilgrimage church of Sad Mother of God from the 13th century; Trstelj as the tallest hill and highest viewpoint in the municipality with organised mountain trails and the mountain hut ''Trstelj''; Cerje, a hill offering a fantastic view of the Vipava Valley, the sea and the Gulf of Trieste, with a mighty monument dedicated to the defenders of the Slovene territory that will gain the final image, and museum collections in the next years.

Karst caves (many still unexplored) are as deep as 70 metres and suitable for caving; in this area there are many cycling and walking trails. The World War I sights are included in the developing project called "Path of Peace in Karst". The Vipava river is a popular venue for sports fishing.