Besserstein ruins, Archaeological site and castle ruin in Villigen, Switzerland.

Besserstein ruins are a medieval castle site on elevated terrain in the municipality of Villigen in Aargau. The stone remains and earthworks still show the spatial layout of this former defensive installation.

Besserstein is first documented in 1244 as a fief of the Murbach abbey, held by the Rein estate. On 13 February 1259 Rudolf of Habsburg and his cousin Gottfried of Habsburg-Laufenburg met at the castle; that April they renounced the advocacy of St. Amarintal in the Vosges in favour of Murbach. The Rein estate passed to the Habsburgs in 1291, and by 1305 the castle was already recorded as a Burgstall, an abandoned site.

The site displays typical features of a medieval fortification as it existed in this region. The visible structures help visitors understand how settlements were protected in that period.

The ruin lies on the eastern edge of a rock spur of the Geissberg at 550 m above sea level. A 200-metre-long rampart, still about 4 metres high, with a ditch in front protects the west side. The enclosed area measures roughly 45 by 25 metres; only the tower base remains visible.

The castle was already described as a Burgstall, an abandoned castle site, in 1305, so it had been given up only a few decades after Count Rudolf of Habsburg and his cousin Gottfried met there in February 1259. The surviving rampart is about 200 metres long and still roughly 4 metres high.