Kostanjevica na Krki is a small town with 700 inhabitants and is the smallest town in Slovenia and the center of Kostanjevica na Krki municipality. The central part of the settlement lies on an artificial island on the Krka River on the outskirts of the Gorjanci Hills. The name of the place is supposed to be derived from the word "Kostel", a fortified church with a camp.
The settlement is an important cultural and artistic center of the Dolenjska region, and its center is today under monumental protection. Kostanjevica was first mentioned in written sources as a town in 1210; in 1249 it acquired market rights. In the late Middle Ages, it was an important Carniolan market settlement. It lost its importance after several Turkish incursions in the 15th and 16th centuries. Kostanjevica later became a rural settlement but maintained its town status.
The development of the settlement began with the establishment of the Cistercian monastery Fons Beatae Mariae, which was founded in 1234 by the Duke of Carinthia Bernard Spanheim as opposition to the Patriarchate of Aquileia and the Counts of Meran. The monastery was a branch of the Viktring monastery near Klagenfurt. In the early 18th century, it was rebuilt in Baroque style, and in 1785 it was abolished by the Austrian Emperor Joseph II.
Kostanjevica is the oldest (since 1252) and at the same time the smallest town in the Dolenjska region. With the old town center on the artificial island on the Krka River, at the foot of Gorjanci, it developed near the Landstrost Castle. Due to frequent floods, the town has gained the nickname "Venice of Lower Carniola". In 1955, the settlement was renamed from Kostanjevica to Kostanjevica na Krki. In 2000, the National Assembly awarded Kostanjevica the status of a town.