The ruined fortress of Salgó sits on a 625-metre volcanic plug north of Salgótarján and is the city's defining sight. The hike up takes about thirty to forty-five minutes from the parking lot at Eresztvény, mostly through beech forest on a well-marked path. The last stretch is steep enough to need both hands.
The views from the keep are excellent on a clear day: the basalt towers of the Karancs ridge to the north, the Hungarian plain unfurling south, and on lucky days the High Tatras visible on the horizon. Partial restoration in the 1990s rebuilt the walls and the bastion enough to give a sense of the medieval layout. Take water; there is nothing on the rock itself.