Castle of the Knights Hospitaller in Słońsk

From the 15th century Słońsk, 12 km from the German border, was the seat of the Brandenburg branch of the Knights Hospitaller. Their castle was rebuilt in the 17th century as a Baroque palace on Dutch models, housed the order’s museum and archive in the 19th century, and was set on fire in 1975. Almost fifty years after the fire, and after several years of conservation work, the ruins are open to visitors again.

History: an order’s seat and a Dutch palace

On 20 March 1426 the Order of St John bought the town and castle of Sonnenburg, as Słońsk was then called, and made it the seat of the Brandenburg Hospitallers, with the castle as the commander’s residence. In 1427–1429 they built a castle on the site of an earlier knight’s manor; its thick medieval walls are still embedded in the ruins. Between 1545 and 1564, under Master Thomas Runge, the castle was remodelled in Renaissance style, and Matthäus Merian recorded its appearance in a copper engraving. In 1652 the Swedes burned it.

Rebuilding was begun in 1662 by the order’s master, Prince John Maurice of Nassau-Siegen, and continued until 1688. The palace was modelled on his residence in the Netherlands designed by Jacob van Campen and Pieter Post, and the work was led by the Dutch master builders Cornelis Rykwaert and Gorus Peron. The complex was laid out on a square plan: the residential building to the east, a courtyard enclosed by a low wall, a moat and a garden on the main axis. In the 19th century the order’s museum and archive were installed here. After 1945 it served as a cultural centre, but around 1970 it was abandoned and in 1975 set on fire.

What to see

• The secured walls of the palace, with Baroque window and doorway surrounds and remnants of decoration above the openings.
• Traces of the medieval castle hidden in the thick ground-floor walls.
• The parish church of Słońsk, Gothic, built 1475–1522, with star vaults, late Gothic wall paintings and a late Renaissance alabaster altar of 1626 brought from the Hohenzollern palace in Berlin.
• The Sonnenburg Martyrdom Museum – in 1933 one of the first Nazi high-security prisons was set up here. On the night of 30–31 January 1945 the SS shot 819 prisoners.

Tripto tip

The castle ruins are open to visitors on Saturdays and Sundays, in summer from 10:00 to 15:00. Visits on weekdays and for groups must be arranged in advance by email (zamek@slonsk.pl) or phone. Allow 30–60 minutes. More than 80% of the Słońsk municipality is protected, and the village has a museum and education centre of the Warta Mouth National Park, opened in 2022 – a good reason to combine the castle with a visit to the national park.