Thonet Castle

The symmetrical building with a raised three-story central section and two-story side wings under hip roofs features a strict historicist facade on the square side with a rusticated plinth zone and pilaster strips, and on the garden side, a portal-balcony-window group on the central risalit and the alliance coat of arms of Salm/Liechtenstein from the mid-19th century in the stepped gable. The core Baroque nave of the monastery is preserved in the central risalit. The former barrel-vaulted church vaults are preserved in the upper floor in the ballroom. The vaults were decorated with Neo-Baroque stucco in the third quarter of the 19th century.

The equally listed Museum Park was opened in 1957 and includes a Baroque fountain basin, a Pietà group on a pedestal from 1756, a dog figure from the Romanesque temple built in 1827 on the Hundskogel in Hinterbrühl, three inscribed tombstones from the 16th and 17th centuries, a Protestant stone with Wolfgangus and Zezilia Reitperger, Protestant councilor and market judge from 1581, a fragment of a Gothic column damaged in 1529 and 1683 from the St. Stephen's Cathedral workshop.

The museum documents the formation of the Mödling landscape, displays rocks and fossils; prehistory, and also features one of Austria's first Avar collections. Historical events, such as Mödling's fate in the Turkish Wars, are documented, as are the biographies of famous residents of the city, such as Mitsuko Coudenhove-Kalergi or the anatomist Josef Hyrtl.

Parts of the museum come from the private paleontological collection of local historian Oskar Spiegel. It was acquired for the museum with the support of the federal government, the state of Lower Austria, and the city of Mödling.

Another large part is made up of Joseph Hyrtl's library, including editions by Paracelsus or Johannes Wesling. These have been digitized and made available to a wide public on the internet.

Since 2008, the Museum Association has published a semi-annual cultural magazine called medilihha.