The old Celje castle is a castle ruin in Celje and it was formerly the seat of the Counts of Celje. It is located on triadic hill, southwest of Celje city. The castle was a ruin for several decades but today it is in major renovation phase. In its time, it represented the largest fort on the Slovenian territory. The castle was first mentioned in 1322 like a 'purch Cylie'.

Celje tourist board organizes different events at the castle all year around. Most known event held there is called 'Pod zvezdami Celjanov' ('Under the stars of Celje') late in summer and shows life in the Middle Ages. Besides theater, tons of music concerts are held in the castle.

Celje Castle is an important Slovenian tourist attraction visited by approximately 60 thousand people per year. Entry fee for the castle is 2€ per person, children up to 6 years have a free entry.