Simplify the following text for a Grade 7 native English-speaking person.
Original: Ludwigsburg is a about 12 km northern city in the center of Baden-W Ã 1\/4 rttemberg , of the Stuttgart city center .
Simplified: Ludwigsburg is a city in Baden-W Ã 1\/4 rttemberg , Germany , about 12 kilometers ( 7.5 miles ) north of downtown Stuttgart , near the river Neckar .