Steel Construction: In the 19th century cast-iron girders were first used for roof construction (Dianabad and Sophienbad swimming baths in Vienna, 1841-1845; Vienna State Opera, opened in 1869). Iron constructions were also used for covered passageways (for the first time in Vienna in 1845), station halls (Wiener Westbahnhof and Nordbahnhof stations, 1857-1865), the Rotunde (1873) and abattoirs (Vienna 1880-1883). In building construction, the first iron and steel constructions were used for the "Eisernes Haus" ("Iron House") in Graz (1848) and for the Haas-Haus building in Vienna (1865-1867). From 1849 the structural elements for many buildings were supplied by the Viennese steel construction firm Gridl (e.g. for the Palm House in the gardens of Schönbrunn Palace, 1882). The first steel-framed buildings (still with facings) date from the time between the two world wars (high-rise building in Herrengasse street, 1st district of Vienna, 1931-1933, tobacco factory in Linz, 1932). The office tower of the Zeltweg ironworks (Styria) was built as an all-steel structure in 1961/62.