The mansion of the commandery of St. John in Łagów, referred to as the House of the Order of St. John by the inhabitants of Sulęcin, is a two-storey building, built on a rectangular plan, located in the direct vicinity of the medieval fortifications. The date of the construction of the original building in Sulęcin is not known. The earliest mention of the construction dates back to 1536.
The present building was built at the turn of the 18th and 19th century in the place of the previous building. An early 18th century drawing by Petzold presents a half-timbered building standing in the place of the present building. A design of 1724 presents a building located at Młynarska Street, beyond the town walls - it was referred to as Ordens Burglehn, e.g. a feudal house. A design of the 1930s describes the building as Johanniter Ordenhaus. The surname of the architect who designed the mansion in Sulęcin is not known, unfortunately. Following the secularization of the Order of St. John, the building became a state possession. It was a residential house, and after 1945 there were council flats in it, and in 1978 it was abandoned and started falling into ruin. In 2008 the building was thoroughly renovated. At present, it houses the Polish-German Cooperation Centre. It is a unique example of a classicist manorial residence in the Sulęcin District.