This branch of the Celje Regional Museum's collection is housed in a grand Renaissance building called the Old Count's Mansion. The 1st floor is home to a dozen rooms featuring interiors from the baroque to Secessionist periods with the museum's show-stopper Celje Ceiling (Celjski Strop) looming down on the central main hall. This enormous trompe l'oeil painting of columns, towers, frolicking angels, noblemen and ladies was completed in about 1600 by an unknown Italian artist.
On the ground floor you'll find glassware displays as well as a small but interesting exhibit on Celje's own Alma M Karlin (1889–1950), the most daring and voracious early-20th-century traveller you've probably never heard of. From 1919 to 1927 Karlin globe-trotted solo, taking in places as diverse as Japan, New Caledonia, New Zealand and Peru and picking up nine languages along the way. Various ethnographic objects she collected on her travels are displayed here as well as photos and information (in Slovene; staff will hand you an English-language pamphlet) on her extraordinary life.
The museum's biggest highlight, however, is a very recent discovery. Excavations inside the cellar (which usually houses the lapidarium) have unearthed the remains of a 1st-century Roman villa replete with vividly coloured, intact frescoes (the only intact Roman frescoes discovered in Slovenia). Preservation work was still ongoing during our last visit, scheduled to be completed in early 2019. Once opened to the public, the in situ frescoes will be the star attraction.