Städtisches Museum Rosenheim (Rosenheim City Museum) opened on 1 June 1895 in the last surviving city gate, which is also the city's oldest building. The gate known as the Mittertor now houses a 550 m² exhibition on local history and geography, with exhibits from across the centuries from Roman times to the 1950s. With around 20,000 objects, 5000 of which form the permanent exhibition, the Städtisches Museum collection is one of the largest in south-east Bavaria.
The museum was established on the initiative of master glazier Josef Gietl (1828-1918), the first chair of the municipal advisory body. Initially, the collection comprised 641 exhibits in four rooms. By the summer of 1902, it had grown to 4000 objects and more space and a redesign were needed. The town council turned to the Rosenheim town archivist and founder of the Historischer Verein (Historical Association) in Rosenheim, Ludwig Eid (1865-1936) and the Munich-based architect and folklorist Franz Zell (1866-1961). The redesigned Städtisches Museum, now comprising ten rooms, reopened on 27 September 1902.
Around thirty years later, there was another major redesign of the local history and geography collection, and this and the subsequent redesign were once again under Franz Zell. The museum opened in May 1932 with a further seven exhibition rooms. Opened in July 1952, the Roman collection was the last addition for around fifty years.
The exhibition space was expanded into the second floor of the neighbouring Gietlhaus between 1996 and 1998. The Gietlhaus had once been the home and office of Josef Gietl, on whose initiative the Städtisches Museum had originally been set up. A new town history section opened in nine rooms of the Gietlhaus on 30 June 1998.
Today, the collection of the Städtisches Museum Rosenheim covers various topics and exhibits on the history of the town and life in the region: archaeological finds from the 17th century that bear witness to Rosenheim's importance as a pottery centre, exhibits testifying to local religious practices and items from the everyday life of the local population right up to the 20th century and the years of Germany's economic miracle. The displays and room layouts from 1902, which back then were already dedicated to the folk art of bygone eras, can still be viewed in their original form today.
There are now 23 exhibition rooms in all at the Städtisches Museum. The museum regularly runs historical, cultural history and folklore and ethnology special exhibitions. It also hosts exhibitions by contemporary artists from the region.