Schloss Hagenberg im Mühlkreis, Medieval château in Hagenberg im Mühlkreis, Austria

Schloss Hagenberg im Mühlkreis is a medieval castle in Upper Austria that sits on a steep mountain ridge with a distinctive gate tower that serves as the town's landmark. Today it operates as a multipurpose complex housing a restaurant, municipal offices, a wedding ceremony room, and spaces for events.

The castle was first mentioned around 1370 as a small fortress and changed hands several times throughout the centuries. After a period of decline beginning in 1928, it was eventually restored and converted to serve its current functions as a cultural and administrative site.

The castle houses the Research Institute for Symbolic Computation of Johannes Kepler University Linz, which moved in during 1989. This blend of academic research within historic walls gives the place a distinctive character that mixes scholarly work with heritage preservation.

The castle stands on a ridge above the Visnitz valley, and the third courtyard, the medieval core, is now covered by a glass roof and used as a lobby. Part of the building serves as the municipal centre, so some areas are in everyday local use. The former outer bailey was separated from the main castle by a moat that has since been filled in.

The gate tower, added in 1892 on the former bergfried, carries a wedge roof flanked by four corner turrets with onion domes; its outline is so recognisable that the municipality uses the tower in its coat of arms. The third courtyard, where the medieval castle is still visible, is now covered by a glass roof and serves as the lobby.