The Mihelčić family mill, better known as the Popović mill has stood on the main and oldest Delnice street for more than 85 years. The construction of the mill began in 1924, when Josip and Francika Mihelčić returned to their home region after years of working in the US. The mill was built for almost a year by two craftsmen from Austria, assisted by a few locals. The facility was fitted with parts of the mill made by the company Ganz Danubius from Budapest, and once finished, it represented the first facility in Delnice operating on electricity from the small hydro power plant in the Zeleni Vir (Green Vortex) spring.

Fun fact: Delnice was not fully electrified with low-voltage current until November of 1927, which makes the mill and a few other commercial and industrial facilities in the Delnice area all the more significant.

The services of the Popović mill were used not only by the Delnice locals, but people across the Gorski Kotar region. The mill operated with two milling lines, one using a stone mill, and the other (more modern one) using iron rolls. Today, both are found on the ground floor, while the attic contains sieving and product drying systems. All the equipment (mills, elevators, sieves, electric engine, leather belts used for power transmission to the machines, etc.) were preserved in their original form and can be toured, and their products can even be enjoyed today. In 1925, during the construction, a commercial building with a linen closet was also built by the mill. The area has since been renovated and today, it is used for art, music and bread baking workshops.