Gotha did not just produce pioneers in the fields of the education system, aristocracy research and the insurance business but is also home to the founding site of the oldest German socialist party, the SPD, with the Tivoli. A party conference took place in the “Kaltwasserscher Saal” (as Tivoli was called back then) in May 1875 where the General German Workers’ Association led by Ferdinand Lassalle and August Bebel’s Social Democratic Workers’ Party were merged into the Germany’s Socialist Workers’ Party and the SPD was born (renamed in 1890).

After the building had been subsequently used as a military hospital and kindergarten, among other things, a monument was set up in 1953. After German reunification, the city, district and Thuringian regional association of the SPD was re-founded in the historical rooms. On this occasion, Willy Brandt held his famous speech at a mass rally on the Hauptmarkt, in which he stated: “Now what belongs together will grow together.” A permanent exhibition on the history of German social democracy focusing on Gotha has been displayed in the building since 2006, in addition to special temporary exhibitions.