Alt-Falkenstein Castle in the municipality of Balsthal (canton Solothurn) was built in the twelfth and thirteenth centuries in the Balsthaler Klus. On the other side of the Balsthal lies Neu-Frankenstein from the same period. The castles of Alt-Bechburg and Neu-Bechburg near Oensingen also date from this period. The Bechburg and Falkenstein dynasties and the Bishop of Basel were the rulers of this area during this period.
The trade and road through the Klus of the Balsthal were of great importance. That is the reason for the four castles. Alt-Falkenstein also has historical significance for the sometimes tense relations between the cantons of Bern and Solothurn in the fourteenth century.
In 1345 troops of Bern marched through the Klus on their way to Mülhouse to help this town against the soldiers of a coalition of Freiburg, Kyburg, Burgundian nobility, Habsburg and Emperor Lodwijk the Bavarian (1282-1347, Ludwig der Bayer). The peace of Königsfelden (1345) made an end to this war.
However, troops from Solothurn barred at Alt-Frankenstein castle the troops from Bern in 1345. The battle almost led to a (civil) war in the Eidgenossenschaft in the making.
In 1420 the last lord of the castle, Hans II von Falkenstein (died 1426), sold the castle to Solothurn. The castle changed hands until Solothurn became the final owner in 1923.
The renovation of the Knights’ Hall and the establishment of the Heimatmuseum (Local Museum) and other adjustments restored the castle (almost) to its former glory. Moreover, the walk to the castle through the Thal Park is already worthwhile.