Simplify the following text for a Grade 4 native English-speaking person.
Original: The historic town lies in the center of the Berlin Urstromtal glacial valley at the confluence of the rivers Dahme and Spree . Shortly before its conflux with the Spree , the Schlossinsel lies on the Dahme , a small island with KÃ penick Castle .
Simplified: It is at the meeting place of two rivers , the Dahme and Spree .