Over the course of time, the castle fell into disrepair. In 1870 the castle was leased for 99 years from the local authorities by a post-November 1830 Uprising Polish émigré, Count Wladyslaw Broel-Plater (a relative of Emilia Plater, a heroine of the same 1830 Uprising), who had been in Switzerland since 1844. At his own expense he restored the castle, and on 23 October 1870 the Polish National Museum was established. Except for two hiatuses (1927 to 1936 and 1952 to 1975), the museum has existed to the present day — an outpost of Polish culture in Switzerland. In 2008 some Rapperswil residents petitioned local authorities to evict the Polish Museum from its home in the castle, as two historical museum locations ("Stadtmuseum" and Polish Museum) estimated to be too expensive. The museum was conducting a petition campaign to retain the Museum in the castle, but although the "Stadtmuseum" (museum of local history was kept respectively renewed at its location at the nearby "Breny" house at "Herrenberg" in 2012/13, indeed, the future of the Polish Museum remains unsure. Rebuilt by Duke Albert II, since 1354 the castle forms an almost equilateral triangle, and each corner of the castle is reinforced with a tower. The highest tower in the southwest is the donjon, commonly called "Gügeliturm" in Swiss-German language, where the so-called "Hochwächter" warned the residents against approaching danger or fire. The five-sided "Zeitturm", a clock tower in the east, houses three bells and beside a sundial and two large clocks. Between these two towers the castle's six-storey palais is situated. In addition, ramparts respectively battlements are leading to the third tower in the northwest, the so-called "Pulverturm" (powder tower). From 1698 to 1837 there was a drawbridge, at the present lower gate towards the former castle chapel. The French revolutionary troops plundered the castle's interior in 1798. Inside the castle's palais, there is located next to the Polish Museum the "Schloss Restaurant". After hours visits are available by appointment, as well as guided tours for groups, although the castle is just partially accessible for the public. The impressing "Rittersaal" (knight's hall) and the historical wooden architecture, as well some pictures and tapestry include further points of interest.