Simplify the following text for a Grade 7 native English-speaking person.
Original: Wilmersdorf is an inner city locality of Berlin , formerly a borough by itself but since Berlin 's 2001 administrative reform a part of the new borough of Charlottenburg-Wilmersdorf .
Simplified: In 1920 Wilmersdorf became a borough of Greater Berlin GroÃ Berlin . In 2001 it became a part of the new borough of Charlottenburg-Wilmersdorf .