In 1995 the artists sprayed the high wall in an east part of Hamburg (Bergedorf-Lohbrügge). In 1996 The Guinness Book of World Records listed the mural as the highest graffiti in the world. Meanwhile the colors bleached, but the 300 square metre art work is still impressive. Hint: use the foot path from Mendelstraße for a good view.

https://de.wikipedia.org/wiki/Datei:Zeichen_der_Zeit_Hochhaus-Graffiti.jpg