The Hôtel Tassel in Brussels, designed by Victor Horta and regarded as the starting point of the Art Nouveau style in architecture, is a classic example of an elegant and functional Art Nouveau interior. The most prestigious interiors were comprehensively designed by highly-regarded artists in this period. While working on designs attention was paid not only to the decor of main rooms, of which the living room was the most important, but the arrangement of staircases and in case of tenement houses - other common space, including gateways and lifts, was equally significant. In such places stucco ornaments or painting decorations were located and all details were taken care of. Unfortunately, with the time passing, many interiors lost their Art Nouveau character. Several interiors of public utility character and a few examples of tenement house staircases are presented in this chapter.

Henry van de Velde, who worked on interior designs for numerous prominent customers in Belgium, Germany, and Switzerland, was one of the most famous designers. His interesting interior design of a sanatorium, made in the years 1903-1905 to order of the duchess Maria Aleksandra von Reuss, was discovered in Trzebiechów in 2003. The result of his work is also presented in the chapter dedicated to doors.

Designed by Józef Mehoffer in 1905 interiors of the seat of the Cracow Chamber of Commerce and Industry, referred to as the Globe House, especially the interiors of the Meeting Chamber, constitute another interesting example. It is one of the most remarkable interiors of the Art Nouveau period in Poland. The homogeneous design of floral motifs with strong influences of the Zakopane style and the Viennese secession comprise stained-glass windows, as well as a ceiling and wall ornaments and furniture.

Also in 1905, the Association of Physicians in Cracow recruited Stanisław Wyspiański as the designer of the seat décor in Radziwiłłowska Street, where the staircase with the motif of chestnuts in the frieze and balustrade parts, as well as the set of stained-glass windows with the impressive depiction of Apollo Bound presented in the part dedicated to stained glass works, looks particularly attractive. The furniture made according to Wyspiański's design has also been preserved in the Meeting Chamber, where the motif of geraniums was implemented.

Jama Michalika (Michalik's Cave), a cafe popular among the Cracovian bohemia, whose Art Nouveau decor design was made by Karol Frycz in 1910, constitutes another example. The interior is presented on the cover, whereas the stained glass works - in the respective chapter.

The design realized by Stanisław Wysiański for the church of Franciscans in Cracow, with the famous stained-glass windows and polychromes depicting the abundance of the Polish flora, is an outstanding example of the Art Nouveau decor. Lilies, poppies, pansies, common mulleins, forget-me-nots, dandelions, nasturtiums, sunflowers, and other flowers decorate the walls. Unfortunately, this motif did not gain recognition among the members of the committee supervising the church restoration, who did not allow the artist to finish his work.

The interior of a rent tenement house is presented with the example of the living room design from an Olsztyn tenement house. Staircases and gateways are also presented in this chapter. Techniques, which for various reasons could not be used in elevations, were applied in this case. The painting decor, whose interesting examples from Bydgoszcz and Chorzów are presented here, prevails. Landscapes or idylls were its most frequent motifs. The decor of ceramic tiles of floral or geometric motifs was applied in public utility buildings and shops. Tile stoves, which have been preserved in one of the Toruń tenement houses, were similarly decorated. Reliefs and stucco ornaments constituted another element of interior design. They usually served as the frame for painting decor. Staircase as well as flat walls were often covered with wallpaper. Despite the fragility of this material, its examples have survived in several Toruń tenement houses and are presented in the chapters dedicated to floral and geometric details.

Balustrades with shape and form richness are the essential element of staircases. The variety of solutions and creativity of their authors are striking. They were usually wooden elements, but there are also numerous examples of artistic metalwork works. Bannisters and initial posts were decorated with various ornaments, among which flowers enjoyed the highest popularity. Initial posts with depictions of female heads, dragons, and cats also occurred.

Interior doors leading to flats were often decorated similarly to entrance doors. Various fittings, plates with residents’ names, mail boxes, and handles seemed very attractive. However, they have not been presented in the album in order not to violate the residents' privacy.