Naggar was the capital of Kullu for nearly 1,500 years before the seat was moved down the valley in the 17th century. The castle, built in the local style of dry-stone walls reinforced with horizontal timber beams, has survived two earthquakes that flattened most other buildings nearby — a vindication of the technique.
Now run as a heritage hotel by the state tourism corporation, the castle has a courtyard temple, a small museum of valley artefacts, and verandahs with long views across the Beas. Worth a stop on the road between Kullu and Manali; worth a night if you can spare it.