Krško Castle, Castle ruin in Cesta, Slovenia.

Krško Castle is a ruin standing on a hilltop above the Sava River, featuring stone structures from different periods of history. The remains show architectural elements that reflect both medieval and later modifications to the original structure.

Krško was first mentioned in 895, when Emperor Arnulf of Carinthia granted it to the retainer Valtun; whether a castle then stood is unknown. The castle was probably built shortly after 1100 by the Counts of Bogen, whose ministeriales held it by 1154. In 1189 it appears as Castrum Gurkeuelt, when Adalbert of Bogen pawned it to Archbishop Adalbert III of Salzburg for 800 Freising marks, possibly to fund the Third Crusade. In 1202 the Bogen sons sold it to Salzburg for a further 800 marks and received it back as a fief. From 1351 to 1358 it belonged to the Counts of Celje; after Ulrich II's death in 1456 his widow Katharina sold it to the Habsburgs in 1459.

The castle and the town share their name with the Krka River; the German name Gurckfeld means 'Krško field'. The ruin is registered immobile cultural heritage of Slovenia. In Valvasor's 1689 engraving the castle is still shown intact, a record of how it looked before decay.

The ruins are accessible by following marked trails through the area, which are straightforward to navigate. The location in the Municipality of Krško in eastern Slovenia is well connected to local walking paths.

The ruin sits on a hillside with views overlooking the Lower Sava valley and surrounding hills of Lower Carniola. From this elevated vantage point, visitors can understand the landscape and the strategic importance of the former defensive position.