The Karlsruhe House of Estates was the first new parliament building in Germany and represents the 125 years of Baden parliamentary history. The basis was the Baden Constitution, which granted modern political rights of participation for the first time and was signed by Grand Duke Karl in 1818.

The chief municipal architect Friedrich Weinbrenner had been instructed by the members of parliament to design a new building. Weinbrenner opted for a distinctive emphasis of the street corner on Friedrichsplatz in the form of a rotunda. At the beginning of 1821 and due to excessive costs, Weinbrenner was replaced by his nephew and pupil, the military building director Friedrich Arnold, who only made insignificant modifications to the plans, however. These included a mezzanine level and fewer but partly larger rooms. The budget was ultimately exceeded by more than half.

The electoral law reform and the increase in the number of members of parliament in the Second Chamber made an extension building necessary in 1905. The architect Karl Henz of Karlsruhe built on Ritterstraße to the north. This building – now the Labour Court – still stands today.

The House of Estates suffered serious damage in the war. The state, as the owner, saw no need to reconstruct it after 1945 and let the ruins fall into decay. Despite criticism, the city began demolition work on the remains in 1961. The plot was divided; the western section went to the Catholic Church for building the St. Stephan Community Centre. The remaining 930 m² wasteland was kept as a car park. The city purchased this site in 1987 and built the “Neue Ständehaus” (New House of the Estates), containing the municipal library and the House of the Estates memorial, in 1993 in recognition of the historical significance.

The firm of architects Planfabrik SPS took up the motif of the rotunda and conical roof of the historical predecessor. The facade of the new building is modern in design and is finished in light-coloured artificial stone but fits in well with the proportions and lines of the neighbouring property. It looks as if it has three floors but it actually conceals a fourth and fifth floor beneath the prominently protruding cornice and roof truss.

The new House of Estates also has a museum-like quality, remembering the history of the Baden Constitution and the democratic tradition of the Federal Republic of Germany. Baden was the most liberal of all German states and the Baden Constitution was far ahead of its time. It guaranteed equality before the law, protection of property, protection of personal freedom, freedom of the press, freedom of thought, and a right to vote, initially only for men but then, in the 20th century – also as the first German state – for women as well.