Next to the Topographie des Terrors is the Martin Gropius Bau – a neo-Renaissance exhibition center designed by the great-uncle of Bauhaus founder Walter Gropius. The Berlin Wall was directly at the south side of the street but the pavement was still East Berlin territory meaning that the exhibition center in West Berlin could not be entered through its main entrance without leaving the country first. Until re-unification in 1990, only the side entrance was used.