St. Johannsen Abbey, Benedictine abbey in Gals, Switzerland.

St. Johannsen Abbey is a substantial stone religious complex in Gals featuring traditional Benedictine monastic design with multiple wings and connecting corridors. The compound displays typical features of monastic layout including cloisters, residential buildings, and service areas arranged around central courtyards.

The monastery was founded as a Benedictine community and operated as a religious center for centuries before its closure in 1528 following the Swiss Reformation. After dissolution, the building underwent several changes in use before arriving at its present function.

The name St. Johannsen, still used locally, replaced Erlach after the 1528–1529 secularisation, when the abbey became a Bernese bailiwick. The former abbey church lost its nave, and the surviving choir and transept served as a grain store. Since 1883 the site has housed a prison, and since 1978 a concordat centre for adult men.

The site is not open to the public today as it houses a correctional facility and operates under security measures. Visitors can view the outer structures of the historic complex from outside and gain an impression of the architecture from a distance.

The abbey church's choir and transept survived the 1528 secularisation as a grain store, but by 1961 they were unsafe and were demolished. The choir was rebuilt in 1970–1971; the nave had already been pulled down in the 16th century and was never restored.