Neu-Falkenstein Castle, Castle ruin in Balsthal, Switzerland.

Neu-Falkenstein is a castle ruin set on a rocky spur above the Swiss town of Balsthal, with walls still standing around 50 feet (16 meters) tall. The remains include a prominent residential tower and sections of the surrounding curtain wall that give a clear sense of the original layout.

The castle was probably built in the early 12th century by a local noble family; the brothers Welf and Ulrich von Falkenstein appear in a 1145 document of doubtful authenticity. In the early 13th century a branch of the Bechburg family settled here as counts of Falkenstein and added a large hall building and a round keep. The Basel earthquake of 1356 caused damage whose repair came close to a new build, hence the name Neu-Falkenstein. In 1374 Henmann von Bechburg robbed a Basel merchant convoy of saffron near St. Wolfgang; a 14-week siege followed, the castle was taken and partly destroyed, and sixteen defending mercenaries were beheaded in the courtyard. Solothurn acquired it in 1417 and kept a bailiff here until 1798.

The name Neu-Falkenstein (New Falkenstein) marks it as the later of two castles: Alt-Falkenstein, built around 1250 by Rudolf von Falkenstein on the valley side, still stands opposite. The ruin is a Swiss heritage site of national significance. The castle's own name is thought to reflect the near-rebuilding after the 1356 Basel earthquake.

The ruin is reached on foot from Balsthal along well-marked hiking trails, with the climb taking around half an hour at a moderate pace. The rocky path can get slippery in wet weather, so sturdy footwear is a good idea.

The castle's name is misleading: despite "Neu" (new), it is thought to be older than Alt-Falkenstein on the opposite side of the valley. Around 1250 Rudolf von Falkenstein founded Alt-Falkenstein and a fortified outer bailey at the foot of the castle rock.