Built 1714 as "Ball-und Caffee-Haus" by converting a brewery. Used as an university ballroom and theatre. Subsequently used for theatre performances by touring companies (until 1868 also known as "Stadttheater"). 1782 rebuilding and redecoration. 1808 redecoration by Horny and Carl Heidloff for the "Congress of Erfurt", whose participants included Napoleon I. and the Czar Alexander.

1822 major rebuilding. Re-opened 26 Dec 1822 with Goethe's "Egmont". 1831 extension by a neighbouring house, facade rebuilding. 1847 redecoration. 1870 converted into a concert hall and ballroom, renamed "Kaisersaal" in memory of the 1808 "Congress of Erfurt". 1891 site of the first major national Social Democratic Party (SDP) convention. 1900 interior alterations. 1918-1938 used as a variety theatre and cinema. 1920 interior alterations. 1945 renamed "Erfurter Kongreßsäle". 1959 exterior renovation. Ca. 1965 renamed "Kulturhaus des Büromschinenwerkes Optima Erfurt". Closed 1982 due to safety concerns.

1991-1993 major renovation, interior restoration to the 1870 designs. Re-opened 1994. Used for congresses, various theatre performances and concerts, balls, and various other events. The complex inlcudes the "Kaisersaal" (up to 650 seats) and 6 function rooms.

Links: www.kaisersaal.de, Wikipedia