Rapid economic development was fuelled by the opening of the Southern Railway which brought more immigrants to the town, especially Germans, who also brought with them a new lifestyle and mode of thinking. New prominent buildings were constructed along the main urban arteries, such as the "Šemalna" barracks along today's Gergorčičeva Street (1884), the new theatre (1885), modern hospital and savings bank (1887), the territorial army barracks in Gaberje (1894), Narodni dom (1897), state post office (1898), girls' public school (1905), the German House (1907), boys' public school (1912) etc., while older buildings were extended with new floors and refurbished with ornate façades. In 1889, the municipality adopted a resolution that water be drained from the roofs through the gutters and drains, and that new buildings in the old town centre should not have less than one floor in addition to the ground floor.
In 1872, the first municipal gas works were built (in Glazija) which also allowed public gas lighting, replacing the previously used oil lamps (1873). In the same year, building owners received a decree by the municipal authorities that the areas in front of their houses – pavements – had to be paved. Previously neglected gravel streets were paved with granite blocks.
In the 1870s, sanitation was greatly improved as well. At first, they problem of cesspool emptying and disposal of faecal water was resolve. Later, a modern sewage system was built. The sewage system in the centre of the town relied on the old Roman sewer system; after 1890, the brick channels were replaced with concrete sewer pipes.
In the 1890s, the municipality started to plan the fresh water pipeline. Although there were 16 wells with quality potable water in town, these were compromised by potentially contaminated groundwater during every storm, putting the citizens' health at risk. The Celje water supply system, originating in Fužine near Vitanje, was completed in 1908.
Another improvement was launched in Celje a year before World War I as the power plant in the Westen enamelled kitchenware factory started to supply power to the Celje public street light system.