Simplify the following text for a Grade 7 native English-speaking person.
Original: Heidelberg is a German city situated in the south-west of the country . It is the fifth largest city of the German State of Baden-W Ã 1\/4 rttemberg after Stuttgart , Mannheim , Karlsruhe and Freiburg im Breisgau .
Simplified: Heidelberg is a city by the Neckar river in the south-west of Germany in the state of Baden-W Ã 1\/4 rttemberg .