The Castle of Ljubljana (Slovenian: Ljubljanski grad) is a medieval architectural monument, standing on the Castle Hill (Slovenian: Grajski grič) in the middle of the city Ljubljana, the capital of Slovenia. Excavations prove that the hill was already fortified in the days of the Celts and the Illyrians, and that the Romans had a military post there. The beginning of the medieval castle dates back to the 9th century, although the construction was mentioned for the first time in 1144. At the time it was the seat of the ruler of the province of Spanheim, who even minted his own coins. The current form was reached after the earthquake of 1511 and with further renovations in the beginning of the 17th century. The castle was inhabited by the provincial rulers until the first decades of the 17th century. Later it became a simple garrison and provincial prison.
The renovation of the castle is now almost complete, the two honeymoon suites, the tower, the chapel and the cafeteria are open to the visitors, while the rest of the reconstructed building is normally used for performances, exhibitions and social functions. Part of the renovation is the facade cleaning and the application of a protective coating against atmospheric pollution, moisture and graffiti.
Because of the invisible nature of the GRAFFITIGUARD and the many European references (also on monuments) this system was chosen by Sisapi and the municipality.