The German Open [1] (currently known as the Grass Court Championships Berlin or bett1open) is a WTA Tour affiliated professional tennis tournament for women played in West Berlin, West Germany (until 1990), then Berlin, Germany from 1991 to 2008 following reunification. Held since 1896, it was one of the oldest tournaments for women.
https://en.wikipedia.org/wiki/German_Open_(WTA)