Black Form – Dedicated to the Missing Jews, Memorial in Altona, Hamburg, Germany

Black Form – Dedicated to the Missing Jews is a black cuboid built from aerated concrete blocks, 5.5 metres long, 2 metres high and 2 metres deep, standing at the southern end of Platz der Republik. It faces the white neoclassical Altona Town Hall about 60 metres away along the square's axis. Sol LeWitt designed it in 1987; it carries no inscription.

The monument was installed in November 1989 to commemorate the Jewish residents of Altona who suffered persecution and deportation during the Nazi period. Its establishment came shortly after the fall of the Berlin Wall and marked an important moment in Germany's approach to remembering this history.

Sol LeWitt's title names the Jews of Altona who are absent for good, not only those murdered in the camps and those who emigrated but also their unborn children and grandchildren. The sculpture itself carries no inscription, in keeping with LeWitt's approach; since 1992 two panels placed to its right and left by the Stadtteilarchiv Ottensen explain the work and sketch the history of Altona's Jewish community.

An information panel from the Stadtteilarchiv Ottensen stands near the monument, offering visitors background details and context for their visit. The site is located right at the town hall and is freely accessible at any time, making it possible to visit throughout the day or evening.

Sol LeWitt called the Black Form "the most important piece I ever made" and donated his fee to the Foundation for the History of the German Jews. The sculpture itself carries no inscription; two explanatory panels were added at its sides in 1992 on the initiative of the Stadtteilarchiv Ottensen.